The Pennsylvania Turnpike is a toll highway operated by the Pennsylvania Turnpike Commission in the Commonwealth of Pennsylvania in the United States. A limited-access highway, it runs 360 miles (580 km) across the state. The turnpike designation begins at the Ohio border in Lawrence County, where the turnpike designation continues as the Ohio Turnpike. The designation ends at the New Jersey border at the Delaware River – Turnpike Toll Bridge over the Delaware River in Bucks County, where it continues into that state as the Pearl Harbor Memorial Extension of the New Jersey Turnpike.

The roadway runs an east-west path through the state, connecting the Pittsburgh, Harrisburg, and Philadelphia areas. As it passes through the Appalachian Mountains in the central part of the state, the turnpike utilizes four tunnels. It is part of the Interstate Highway System and is designated as part of Interstate 76 (I-76) between the Ohio border and Valley Forge, I-70 and I-76 between New Stanton and Breezewood, and I-276 between Valley Forge and the New Jersey border. The road uses a ticket system of tolling between the Warrendale and Delaware River Bridge toll plazas. An additional eastbound toll plaza is located at Gateway near the Ohio border. E-ZPass, a form of electronic toll collection, is accepted at all toll plazas.

The Pennsylvania Turnpike was planned in the 1930s to improve automobile transportation across the mountains of Pennsylvania. It utilized seven tunnels that were built for the abandoned South Pennsylvania Railroad in the 1880s. The road opened on October 1, 1940 between Irwin and Carlisle as the first long-distance limited-access highway in the United States that led to the construction of other limited-access toll roads and the Interstate Highway System.

Following World War II, the turnpike was extended east to Valley Forge in 1950 and west to the Ohio border in 1951. In 1954, the road was extended east to the Delaware River. The mainline turnpike was completed in 1956 when the Delaware River bridge was finished. In the 1960s, an additional tube was bored at four of the two-lane tunnels while the other three tunnels were bypassed. These improvements made the entire length of the highway four lanes wide. Improvements continue to be made to modernize the road, such as rebuilding the original section to modern standards, widening portions of the turnpike to six lanes, and the addition of new interchanges.

The Pennsylvania Turnpike runs east-west across Pennsylvania from the Ohio border in Lawrence County to the New Jersey border in Bucks County and passes through the Pittsburgh, Harrisburg, and Philadelphia areas along with farmland and woodland. It crosses the Appalachian Mountains in the central part of the state and uses four tunnels. The Pennsylvania Turnpike Commission controls the highway. This commission was created in 1937 to construct, finance, operate and maintain the road. Five members comprise the commission, including the secretary of the Pennsylvania Department of Transportation and four other members appointed by the Governor of Pennsylvania. In 2010, the roadway had an annual average daily traffic count ranging from a high of 118,000 vehicles between I-476 and Pennsylvania Route 309 (PA 309) to a low of 11,000 vehicles between the Ohio border and I-79. As part of the Interstate Highway System, the entire length of the turnpike is part of the National Highway System.

The Pennsylvania Turnpike begins at the Ohio border in Lawrence County, beyond which it continues west as the Ohio Turnpike. From the state line, the turnpike heads southeast as a four-lane freeway designated as I-76 through rural areas. A short distance from the Ohio border, the eastbound lanes come to the Gateway toll plaza. Immediately after, the tollway crosses into Beaver County, where it reaches its first interchange in the state with I-376 (the Beaver Valley Expressway) in Big Beaver.

Past this interchange, the turnpike reaches the exit for PA 18 in Homewood before it crosses over the Beaver River on the Beaver River Bridge. Farther east, the road crosses into Butler County, where it reaches Cranberry. In this community, the route has an interchange that provides access to U.S. Route 19 (US 19) and I-79. At this point, the turnpike continues through a mix of rural land and suburban residential development to the north of Pittsburgh and enters Allegheny County.

The road comes to the Warrendale toll plaza, which is where toll ticketing begins. From here, the highway continues southeast and has an interchange with PA 8 in Hampton Township. Past this exit, the turnpike runs through more suburban areas and woods and comes to the Allegheny Valley exit in Cheswick, which provides access to PA 28 via Freeport Road. East of this interchange, the road heads south and crosses over the Allegheny River on the six-lane Allegheny River Turnpike Bridge.

Immediately after the Allegheny River, the turnpike becomes four lanes again and passes through the Oakmont Country Club. The highway heads to the southeast and reaches Monroeville, an eastern suburb of Pittsburgh where the turnpike has an interchange with I-376/US 22 (Penn–Lincoln Parkway), providing access to Pittsburgh. After Monroeville, the turnpike continues through suburban and rural areas into Westmoreland County. Here, it heads south to the exit for US 30 in Irwin.

Past the Irwin interchange, the Pennsylvania Turnpike widens to six lanes and heads into more rural areas. It curves southeast and reaches New Stanton, where the turnpike has an interchange that provides access to I-70, US 119, and the southern terminus of Toll PA 66 (the Amos K. Hutchinson Bypass). The roadway narrows back to four lanes at this interchange and I-70 forms a concurrency with I-76 on the tollway. Following New Stanton, the road winds southeast and comes to the exit for PA 31/PA 711 in Donegal. As it continues east past Donegal, the turnpike continues to the east and crosses Laurel Hill into Somerset County.

Within this county, the toll road continues southeast before coming to Somerset. Here, the highway has an interchange with PA 601 that provides access to US 219 and Johnstown. East of Somerset, the tollway passes through more rural areas before coming to forested Allegheny Mountain. Here, the road goes under the mountain in the Allegheny Mountain Tunnel. Upon exiting the tunnel, the turnpike winds down the mountain at a 3-percent grade, the steepest grade along the roadway. Along this stretch, it crosses into Bedford County. The turnpike heads through more forests before entering a valley. The road comes to Bedford, where it has an exit for US 220 Business (US 220 Bus.) that provides access to US 220 and the southern terminus of I-99. This exit serves Altoona to the north.

East of Bedford, the tollway passes through the Bedford Narrows, a gap in Evitts Mountain. The turnpike, US 30, and the Raystown Branch Juniata River all pass through the 650-foot-wide (200 m) narrows. The road winds through a valley to the south of the river before it passes through Clear Ridge Cut near Everett. Further east, the highway comes to Breezewood, where I-70 leaves the turnpike. Immediately after it exits the turnpike, I-70 follows an at-grade portion of US 30 with traffic lights and businesses before it heads south on a freeway alignment.

Past Breezewood, I-76 continues along the tollway and heads northeast across Rays Hill into Fulton County. The turnpike continues east across Sideling Hill and heads through more rural areas. East of the hill, the road reaches an interchange with US 522 in Fort Littleton. After this interchange, the highway parallels US 522 before it curves east and enters Huntingdon County. The tollway heads through the Tuscarora Mountain Tunnel under Tuscarora Mountain, at which point it crosses into Franklin County. In Franklin County, the turnpike curves northeast into a valley and comes to the exit for PA 75 in Willow Hill.

The road heads east again and passes under Kittatinny Mountain in the Kittatinny Mountain Tunnel. A short distance after exiting the Kittatinny Mountain Tunnel, the highway heads through the Blue Mountain Tunnel under Blue Mountain. Upon leaving the tunnel, the turnpike heads northeast along the base of Blue Mountain and comes to an exit for PA 997. East of this interchange, the road crosses into Cumberland County and heads east through the Cumberland Valley on a stretch known as the "straightaway". Further east, the turnpike comes to Carlisle, where it has an interchange with US 11 that provides access to I-81.

As it approaches Harrisburg, the Pennsylvania Turnpike heads east through more rural land with some development. In Upper Allen Township, the turnpike comes to the US 15 interchange that provides access to Gettysburg to the south. The highway continues east through more suburban and rural areas into York County, where it reaches the interchange with I-83 that serves Harrisburg and its western suburbs along with York to the south. East of I-83, the tollway widens to six lanes and crosses the Susquehanna River into Dauphin County on the Susquehanna River Bridge as it bypasses Harrisburg to the south.

Within Lower Swatara Township, the turnpike has an interchange with the southern terminus of I-283, which serves Harrisburg and its eastern suburbs. This interchange marks the point where the road narrows back to four lanes and heads near more suburban development before it continues into rural areas. The turnpike passes through a corner of Lebanon County before it enters Lancaster County.

In Lancaster County, the tollway passes through Pennsylvania Dutch Country. The road reaches an interchange with PA 72 that provides access to Lebanon to the north and Lancaster to the south. Further east, the highway comes to an interchange with US 222 and PA 272 near Denver that serves the cities of Reading and Lancaster. Continuing along, the route passes through more rural areas and heads into Berks County, where there is an interchange with I-176, a freeway to Reading, and PA 10 in Morgantown.

Following this interchange, the turnpike crosses into Chester County and runs southeast. The highway has an exit for PA 100 north of Downingtown, at which point it heads into the western suburbs of Philadelphia. Past this, the road continues east through rural areas and suburban development, where it reaches an E-ZPass-only interchange with PA 29 near Malvern. The tollway enters Montgomery County and comes to the Valley Forge interchange in King of Prussia, where I-76 splits from the turnpike to head southeast on the Schuylkill Expressway toward Philadelphia.

Past the Valley Forge interchange, the turnpike is designated as I-276 and becomes a six-lane road that serves as a suburban commuter highway. The road passes through suburban areas, crossing the Schuylkill River on the Schuylkill River Bridge. In Plymouth Meeting, the turnpike comes to an interchange with Germantown Pike that provides access to Norristown before reaching the Mid-County Interchange. This interchange connects to I-476, which heads south as the Blue Route and north as the Northeast Extension of the Pennsylvania Turnpike.

After the Mid-County Interchange, the mainline of the turnpike heads east through the northern suburbs of Philadelphia to Fort Washington, where there is an interchange with PA 309. A short distance later, the road has a westbound exit and entrance for Virginia Drive that is for E-ZPass tagholders only. In Willow Grove, the highway comes to the PA 611 exit. The turnpike passes through more suburban areas and crosses into Bucks County. In Bensalem, the tollway has an interchange with US 1 that provides access to Philadelphia.

Immediately after, the highway narrows back to four lanes and comes to an E-ZPass-only exit for PA 132, with an eastbound exit and entrance. The road passes through more suburbs and crosses under I-95 without an interchange. Further east, the turnpike reaches the final interchange that provides access to US 13 in Bristol. Right after this exit, the tollway comes to the east end of the ticket system at the Delaware River Bridge toll plaza. The highway crosses the Delaware River into New Jersey on the Delaware River – Turnpike Toll Bridge. At this point, the I-276 designation and the Pennsylvania Turnpike end and the roadway continues east as the Pearl Harbor Memorial Extension of the New Jersey Turnpike, which connects to the mainline of the New Jersey Turnpike. The Pearl Harbor Memorial Extension is an unsigned portion of I-95.

There are many features that characterize the Pennsylvania Turnpike such as the toll system, service plazas, emergency assistance, a radio station, and the speed limits. The highway uses the ticket system for tolling between the Warrendale and Delaware River Bridge toll plazas; a flat-rate eastbound toll barrier is also located at Gateway near the Ohio border. Tolls can be paid with cash or E-ZPass. A total of 15 service plazas along the turnpike provide food and gas along with other amenities. Emergency assistance to motorists is available via callboxes, first responder services, and the Pennsylvania State Police. Traffic conditions for the highway are broadcast on AM 1640. The speed limit for most of the tollway is 65 mph (105 km/h).

The Pennsylvania Turnpike uses the ticket system method of tolling between Warrendale and the Delaware River Bridge toll plazas as well as on the Northeast Extension up to Wyoming Valley. Upon entering the turnpike, motorists receive a ticket that lists the fares for every exit. When exiting, the ticket is surrendered and the appropriate fare is paid. If the ticket is lost, motorists are charged the highest possible fare for that exit. An eastbound mainline toll plaza is located at Gateway near the Ohio border and charges a flat rate. There are no tolls on exit ramps between Gateway and Warrendale. E-ZPass is accepted at all toll plazas. The PA 29 interchange and the westbound Virginia Drive and eastbound Street Road interchanges only accept E-ZPass.

As of 2013[update], it costs a passenger vehicle $33.90 to travel the length of the mainline turnpike between Warrendale and Delaware River Bridge using cash and $26.71 using E-ZPass; the eastbound Gateway toll plaza costs $5.25 using cash and $4.06 using E-ZPass for passenger vehicles. The average toll rate for the turnpike is 10.2 cents per mile (6.3 cents per kilometer).

When the highway was under construction in 1939, the proposed tolls were $1.50 (about $25.00 in 2013 dollars) for a one way trip for cars while a round trip would cost $2.00 (about $33.00 today). Trucks would pay $10.00 (about $167.00 today) one-way. Special fares would be charged for motorists who did not travel the length of the turnpike. Upon opening in 1940, the tolls were set at $1.50 (about $25.00 today) one-way and $2.25 (about $37.00 today) round trip for cars. The tolls were to be used to pay off bonds to build the road and were to be removed once the bonds were paid off. Tolls continue to be charged today to pay for improvements to the turnpike system. It had a toll rate was about one cent per mile (0.62 cents per kilometer), 17 cents per mile (11 cents per kilometer) today, when the turnpike opened. The ticket system was used to pay for tolls.

This toll rate remained the same for the first 25 years as other toll roads such as the New York State Thruway, Ohio Turnpike, Connecticut Turnpike, and Massachusetts Turnpike had a higher rate. In 1969, the turnpike commission announced a 75% toll hike, the first such increase for cars. This rise in tolls, which took place on September 1, brought the toll rate to 2 cents per mile (1.2 cents per kilometer), 13 cents per mile (8.1 cents per kilometer) today. A toll increase of 22% was announced in 1978 and went into effect on August 1 of that year; this raised the rate to 2.2 cents per mile (1.4 cents per kilometer), 8 cents per mile (5.0 cents per kilometer) today.

In 1986, a toll hike of 30% was planned; the new rates started on January 2, 1987. With this increase, the toll rates were brought to 3.1 cents per mile (1.9 cents per kilometer), 6 cents per mile (3.7 cents per kilometer) today. Another toll increase of 30% took place on June 1, 1991 to fund expansion projects; the new rate was 4 cents per mile (2.5 cents per kilometer), 7 cents per mile (4.3 cents per kilometer) today.

On August 1, 2004, tolls increased by 42% to a rate of 5.9 cents per mile (3.7 cents per kilometer), 7 cents per mile (4.3 cents per kilometer) today, to provide money for construction along the road. The turnpike commission raised tolls by 25% on January 4, 2009 in order to provide funds to the Pennsylvania Department of Transportation for road and mass transit projects as called for by Act 44. This toll hike brought the rate to travel the turnpike to 7.4 cents a mile (4.6 cents per kilometer), 8 cents per mile (5.0 cents per kilometer) today. At this point, tolls were planned to increase every year.

A 3% toll increase went into effect on January 3, 2010; the rate was now 7.7 cents per mile (4.8 cents per kilometer), 8 cents per mile (5.0 cents per kilometer) today. Another toll hike occurred on January 2, 2011, where cash tolls increased 10% and E-ZPass tolls increased 3%. The new toll rate was 8.5 cents a mile (5.3 cents per kilometer), 9 cents per mile (5.6 cents per kilometer) today, As part of this toll hike, the turnpike commission initially planned not to print the toll amount on new tickets. As a result of this plan, Pennsylvania Auditor Jack Wagner questioned if the commission was trying to hide the toll hike. The turnpike commission later decided to include the fares on the new tickets.

Cash tolls increased again on January 1, 2012 by 10%; E-ZPass toll rates unchanged from the previous year. With this increase, the toll rate was 9.3 cents a mile (5.8 cents per kilometer), 9 cents per mile (5.6 cents per kilometer). Another toll hike occurred January 6, 2013, where cash tolls rose 10% and E-ZPass tolls rose 2%. With the annual rise in tolls, traffic has been decreasing on the turnpike in favor of local roads.

In 1968, the turnpike commission proposed converting the section of the road between Morgantown and the Delaware River Bridge from the ticket system to a barrier system. This project was deferred in 1971 due to a decline in revenue brought on by the completion of I-80.

Motorists originally stopped at booths to receive toll tickets from turnpike staff. In 1987, ticket machines replaced the workers. An electronic toll collection system was proposed in 1990, where a motorist would create an account and use an electronic device that would be read from an electronic tollbooth. The motorist would be billed later. The multi-state electronic tolling system, which was to be called E-ZPass, was planned to be implemented by 1998. Installation of the system was later pushed back to 2000.

On December 2, 2000, E-ZPass debuted along the roadway between Harrisburg West and Delaware River Bridge. By December 15, 2001, E-ZPass could be used on the entire length of the Pennsylvania Turnpike. Commercial vehicles were allowed to start using the system on December 14, 2002.

On June 1, 2003, the Warrendale toll plaza became the west end of the ticket system. As a result, the Gateway toll plaza became a flat-rate toll plaza and the toll booths at the New Castle, Beaver Valley, and Cranberry interchanges were closed. Express E-ZPass lanes opened at the Warrendale toll plaza in June 2004, which allowed motorists to travel through the toll plaza at highway speeds. In 2005, the turnpike commission announced plans to convert the Gateway toll plaza to eastbound only in 2006 in order to reduce congestion and allow for the construction of Express E-ZPass lanes. The Express E-ZPass lanes at the Gateway toll plaza opened in July 2007.

On November 24, 2004, the day before Thanksgiving, 2,000 Teamsters Union employees went on strike, after contract negotiations failed. This was the first strike in the history of the roadway. As this is usually one of the busiest traffic days in the United States, to avoid traffic jams, tolls were waived for the rest of the day. Starting on November 25, turnpike management personnel collected flat-rate passenger tolls of $2 and commercial tolls of $15 from cash customers on the ticketed system, while E-ZPass customers were charged the lesser of the actual toll or the same flat rates. The strike ended after seven days when both sides reached an agreement on November 30. Normal toll collection resumed December 1.

The turnpike commission announced plans to consider eliminating manned toll booths in favor of all-electronic tolls. With this, tolls will be paid using either E-ZPass or credit cards. Drivers unable to pay by either of these methods will be billed in the mail using license plate recognition; an additional surcharge will be applied. In addition to E-ZPass, the turnpike commission offered other automated options to pay for tolls such as using a prepaid account that utilizes license plate recognition. McCormick Taylor and Wilbur Smith Associates have been hired to conduct a feasibility study on converting the road to all-electronic tolls.

On March 6, 2012, the turnpike commission announced that it was going forward with an all-electronic tolling plan. Such a plan will take at least five years to implement to allow time for equipment to be installed and the reconfiguration of ramps. It will save the turnpike commission $65 million a year on labor costs by eliminating toll collectors. The plans call for a 76% surcharge for motorists who do not have E-ZPass that are billed by mail. This surcharge could raise the toll for someone without E-ZPass to $53.10 to travel the entire turnpike.

The turnpike has a callbox every mile for its entire length. Callboxes were first installed on the roadway between New Stanton and New Baltimore in December 1988. In 1989, the callboxes would be extended along the entire length of the turnpike. Motorists may also dial *11 on their mobile phones. First responder services are available to all turnpike customers via the State Farm Safety Patrol program. The safety patrol program, which is free, look for disabled motorists, debris, and accidents along the roadway and provide assistance. The patrol service is available 24 hours every day of the year. Each patrol vehicle covers a 20-to-25-mile (32 to 40 km) stretch of the turnpike. Towing services are available from authorized service garages located near the highway. Pennsylvania State Police Troop T patrols the Pennsylvania Turnpike. It has headquarters in Highspire and substations along the turnpike grouped into three sections. The western section has substations located in Gibsonia, Somerset, and New Stanton. The central section has substations in Bowmansville, Everett, and Newville while the eastern section has a substation in King of Prussia.

The Pennsylvania Turnpike Commission broadcasts current roadway, traffic, and weather conditions via "Highway Advisory Radio" transmitters at each exit. Broadcasts are available on AM 1640 and can be received approximately two miles away from each exit. Motorists can also receive alerts and information via the internet, mobile phone, a hotline, and message boards at service plazas through the Turnpike Roadway Information Program (TRIP).

The Pennsylvania Turnpike has 15 service plazas located along the mainline throughout the state. These service plazas offer various fast food restaurants such as Burger King, Roy Rogers, Famous Famiglia Pizzeria, Auntie Anne's, Hershey's Ice Cream, and Starbucks, and a gift shop. Each service plaza also has a Sunoco gas station and an A-Plus convenience store. Other amenities are available such as an ATM, pay phone, picnic areas, restrooms, tourist information, and Wi-Fi. A welcome center is also available at the King of Prussia plaza. The New Stanton and Sideling Hill plazas contain a seasonal farmers market.

As the first section of the highway was built through a rural part of the state, food or gas was not easily available to motorists. Due to this, the commission decided to construct service plazas at 30-mile (48 km) intervals. The service plazas would be constructed of native fieldstone resembling Colonial-era designs. In 1940, Standard Oil of Pennsylvania was awarded a contract to operate ten Esso service stations along the turnpike. Eight of the service plazas would consist of service stations along with a restaurant while the service plazas at the halfway point in Bedford would be larger. South Midway service plaza, which was the largest, contained a dining room, lunch counter, lounge, and lodging facilities for truckers; a tunnel connected it to the smaller North Midway service plaza. The remaining service plazas were smaller and contained only a lunch counter. Food service at the service plazas was provided by Howard Johnson's. After World War II, the food facilities were enlarged. Service stations sold gasoline, repaired cars, and had towing services available.

On the extensions of the turnpike, the service plazas were built larger and further back from the road. Gulf Oil would operate the service stations on the extensions; Howard Johnson's still provided food service at sit-down restaurants. With the creation of the Interstate Highway System, restaurants and gas stations were prohibited along Interstate Highways. The turnpike, which became a part of the system, was grandfathered in and allowed to continue operating its service plazas. When the highway was realigned to bypass the Rays Hill and Sideling Hill tunnels, the Cove Valley service plaza on the original section was closed and replaced with the Sideling Hill service plaza, which became the only service plaza on the mainline turnpike that served drivers travelling in both directions.

In 1978, as Howard Johnson's exclusive contract to provide food service was nearing an end, the turnpike commission considered bids for competitors to provide food service. That year, ARA Services was awarded a contract to provide food service at two service plazas, ending Howard Johnson's monopoly. The tollway became the first toll road in the country to offer more than one fast food chain at its service plazas. At this time, gas stations along the turnpike were operated by Gulf Oil, Exxon, and ARCO. Hardee's also opened locations at the service plazas in 1980 to compete with Howard Johnson's. With this, the turnpike became the first road in the world to offer fast food at its service plazas.

Burger King and McDonald's opened along the Pennsylvania Turnpike in 1983. This marked the transition from sit-down dining to fast food along the Pennsylvania Turnpike, as motorists desired fast food. The Marriott Corporation purchased the remaining Howard Johnson's restaurants in 1987 and replaced them with various restaurants such as Roy Rogers and Bob's Big Boy.

Gulf took over the Exxon stations on the turnpike in 1990. Sunoco took over operation of the gas stations along the turnpike from Gulf in 1993, outbidding Shell Oil. In 1995, a farmers market was introduced to the Sideling Hill service plaza.

HMSHost was awarded a contract to reconstruct the service plazas along the turnpike in 2006. The improvement of the service plazas, which is to cost $150 million, will include a food court layout and modernized restrooms. Sunoco continues to operate the gas stations at the renovated service plazas. Oakmont Plum was rebuilt between September 2006 and May 2007. Renovation of Sideling Hill and North Somerset began in September 2007; they were completed in May 2008, were renovated. New Stanton was rebuilt between September 2008 and May 2009. From January 2009 until May 2010, the King of Prussia plaza was reconstructed. Bowmansville and Lawn were renovated from September 2010 to May 2011. Between September 2011 and May 2012, the South Somerset, Cumberland Valley (formerly Plainfield), and Blue Mountain plazas were rebuilt. In September 2012, the Highspire and South Midway service plazas closed for reconstruction; completion is expected in May 2013. The North Midway, Peter J. Camiel, and Valley Forge service plazas are expected to be rebuilt between September 2013 and May 2014.

As part of the deal with HMSHost, the North Neshaminy, South Neshaminy, and Hempfield service plazas were slated to be closed. In January 2007, the Hempfield service plaza closed due to a project to widen the roadway in the area. The South Neshaminy service plaza closed on June 30, 2007 to allow a slip ramp to be built. On May 12, 2010, the North Neshaminy service plaza closed due to the project to build an interchange with I-95. In addition, the Zelienople service plaza closed on November 15, 2008 due to lack of business.

The Pennsylvania Turnpike has several major bridges and tunnels along it. There are four tunnels that pass through the Appalachian Mountains in central Pennsylvania. The Allegheny Mountain Tunnel passes under Allegheny Mountain in Somerset County and is 6,070 feet (1,850 m) long. The Tuscarora Mountain Tunnel heads beneath Tuscarora Mountain on the border of Huntingdon and Franklin counties and is 5,236 feet (1,596 m) long. The Kittatinny Mountain Tunnel and the Blue Mountain Tunnel are located adjacent to each other in Franklin County and are 4,727 feet (1,441 m) and 4,339 feet (1,323 m) long respectively.

There are five bridges that carry the turnpike over major rivers in the state. The 1,545-foot-long (471 m) Beaver River Bridge carries the roadway over the Beaver River in Beaver County. The highway crosses the Allegheny River in Allegheny County on the 2,350-foot-long (720 m) Allegheny River Turnpike Bridge. The tollway crosses the Susquehanna River between York and Dauphin counties on the 5,910-foot-long (1,800 m) Susquehanna River Bridge. In Montgomery County, the turnpike crosses the Schuylkill River on the 1,224-foot-long (373 m) Schuylkill River Bridge. At the New Jersey border in Bucks County, the tollway is connected to the Pearl Harbor Memorial Extension of the New Jersey Turnpike by way of the 6,571-foot-long (2,003 m) Delaware River – Turnpike Toll Bridge over the Delaware River.

The turnpike had no enforced speed limit when it opened except for the tunnels, which had a 35 mph (56 km/h) speed limit. Some drove as fast as 90 mph (140 km/h) on the road. In 1941, a speed limit of 70 mph (110 km/h) for cars and between 50 mph (80 km/h) and 65 mph (105 km/h) for trucks was enacted. During World War II, the turnpike adopted the national speed limit of 35 mph (56 km/h). After the war, the speed limit was returned to 70 mph (110 km/h).

In 1953, the speed limit on the portion of the highway between the Ohio border and Breezewood was lowered to 60 mph (97 km/h) to reduce accidents, but was returned to 70 mph (110 km/h) as it did not have the desired effect. The speed limit on the turnpike was reduced to 65 mph (105 km/h) in 1956 for cars, buses, and motorcycles, with other vehicles limited to 50 mph (80 km/h). A minimum speed of 35 mph (56 km/h) established in 1959. The minimum speed was raised to 40 mph (64 km/h) in 1965.

With the National Maximum Speed Law in 1974, the speed limit on the turnpike was reduced to 55 mph (89 km/h). The speed limit was once again raised to 65 mph (105 km/h) in 1995 outside of urban areas with a population greater than 50,000, with urban areas retaining a 55 mph (89 km/h) speed limit. In 2005, the turnpike commission approved raising the speed limit to 65 mph (105 km/h) for the entire length of the roadway except at the tunnels, mainline toll plazas, and along the winding portion of roadway near the Allegheny Mountain Tunnel. These areas retain a 55 mph (89 km/h) speed limit.

The Pennsylvania Turnpike was planned in the 1930s in order to improve transportation across the Appalachian Mountains of central Pennsylvania. It utilized seven tunnels that were bored for the abandoned South Pennsylvania Railroad project in the 1880s. The highway opened on October 1, 1940 between Irwin and Carlisle as the first long-distance limited-access road in the United States. Following its completion, several other toll roads and the Interstate Highway System were built. The highway was extended east to Valley Forge in 1950 and west to the Ohio border in 1951. It was completed to the New Jersey border at the Delaware River in 1954; the Delaware River Bridge opened in 1956. In the 1960s, the entire highway was made four lanes wide by adding a second tube at four of the tunnels and by bypassing the other three. Since then, many other improvements have occurred, such as the addition of new interchanges, the widening of portions of the highway to six lanes, and the reconstruction of the original section. An interchange is planned at I-95 that will fill a gap in that route.

Prior to the Pennsylvania Turnpike, there had been many other forms of transportation across the Appalachian Mountains of central Pennsylvania. Native Americans traveled across the mountains along wilderness trails. Later, European settlers followed wagon roads in order to cross that state. The Philadelphia and Lancaster Turnpike opened between Lancaster and Philadelphia in 1794. It became the first successful turnpike in the United States. The road was paved with logs, an improvement from the dirt Native American trails. In 1834, the Main Line of Public Works opened as a system of canals, railroads, and inclined planes across Pennsylvania in competition with the Erie Canal in New York.

The Pennsylvania Railroad was completed between Pittsburgh and Philadelphia in 1854. Another railroad known as the South Pennsylvania Railroad was proposed in the 1880s to cross the mountains in direct competition with the Pennsylvania Railroad. It had received the backing of William Henry Vanderbilt, the head of the New York Central Railroad, which was the Pennsylvania Railroad's chief rival. Andrew Carnegie also provided financial support as he was unhappy with the rates charged by the Pennsylvania Railroad. Major construction started on the South Pennsylvania Railroad in 1883, but stopped when the two railroads reached an agreement in 1885. Following the stoppage of construction, the only vestiges of the railroad were nine tunnels, some roadbed, and piers for a bridge over the Susquehanna River in Harrisburg.

In the 20th century, the automobile started to become the main form of transportation. Motorists crossing the mountains of Pennsylvania in the 1930s had to travel along hilly and winding roads such as the Lincoln Highway (US 30) or the William Penn Highway (US 22), which had steep grades exceeding 9%. Due to the sharp curves and steep grades, the roads were dangerous and had many fatalities from various accidents such as skidding.

As a result of the challenges of crossing the mountains of Pennsylvania by car, William Sutherland of the Pennsylvania Motor Truck Association and Victor Lecoq of the Pennsylvania State Planning Commission proposed a toll highway in 1934 to cross the mountains. This toll highway was to be a four-lane limited-access road modeled after the German autobahns and the Merritt Parkway in Connecticut. In addition to improved travel across the mountains, the turnpike was to serve as a defense road. The proposed road was to use the former tunnels of the abandoned South Pennsylvania Railroad project.

In 1935, Sutherland and Lecoq introduced their turnpike idea to state legislator Cliff Patterson. Patterson proposed a resolution to study the idea of a turnpike on April 23, 1935. It passed, and the Works Progress Administration (WPA) was to explore the possibility of building the road. Their study estimated it would cost between $60 and $70 million (between $1.02 billion and $1.19 billion in 2013 dollars) to build the turnpike. Patterson introduced Bill 211 to the legislature, which called for the establishment of the Pennsylvania Turnpike Commission. The bill was signed into law by Governor George Howard Earle III on May 21, 1937. On June 4, 1937, the first commissioners were named. The highway was planned to run from US 30 in Irwin to the east of Pittsburgh east to US 11 in Middlesex to the west of Harrisburg at a length of about 162 miles (261 km). It would pass through nine tunnels along the way.

The road was to have four lanes total with a median in the center and no grade steeper than 3%. Access to the highway would be controlled by entrance and exit ramps. There would be no at-grade intersections, driveways, traffic lights, crosswalks, or at-grade railroad crossings. Curves were to be wide and the roadway signage was to be large. The right-of-way for the turnpike was to be 200 feet (61 m); the road itself was to be 24 feet (7.3 m) wide and have 10-foot (3.0 m) shoulders and a 10-foot (3.0 m) median. Through the tunnels, the road would have two lanes in total, a 14-foot (4.3 m) clearance, and a 23-foot (7.0 m) wide roadway. The design for the turnpike would remain uniform for its entire length.

In February 1938, the turnpike commission began looking into proposals for $55 million in bonds to be issued for construction of the turnpike. A month later, Van Ingen and Company purchased $60 million (about $991 million in 2013 dollars) in bonds, which they would offer to the public. President Franklin D. Roosevelt approved a $24 million (about $396 million in 2013 dollars) grant by the WPA in April 1938 for the construction of the roadway; the state also put up $29 million towards the project. The grant would soon receive final approval from the WPA. Plans were still made to sell bonds; the first issue was planned to be around $20 million (about $330 million in 2013 dollars). The smaller planned bond issue was due to the grant issued by the WPA.

In June, the Reconstruction Finance Corporation (RFC) announced they would loan the commission an adequate amount of money to build the road. This loan from the RFC totaled $32 million (about $528 million in 2013 dollars) along with $26 million (about $429 million in 2013 dollars) of free money from the Public Works Administration (PWA) to provide $58 million toward the construction of the turnpike; the highway tolls would be used to repay the RFC. In October 1938, the turnpike commission came to an agreement with the RFC and the PWA in which the RFC would purchase $35 million in bonds along with the grant from the PWA. That same month, a banking syndicate purchased that amount in bonds from the RFC.

In September 1938, there was a proposal for railroad from Pittsburgh to Harrisburg on the former South Pennsylvania Railroad right-of-way that was to be used for the turnpike, but this was turned down.

In building the turnpike, work took place on finishing the boring of the former railroad tunnels. As the Allegheny Mountain Tunnel bore was in too poor condition to use, a new bore was drilled 85 feet (26 m) to the south. The commission considered bypassing the Rays Hill Tunnel and Sideling Hill Tunnel, but the cost for a bypass was considered to be too high. Crews used steam shovels to widen the portals of the tunnels. Temporary railroad tracks were used to transport construction equipment into the tunnels. Concrete was used in lining the tunnel portals. The tunnels were built to include ventilation ducts, drainage structures, and sidewalks in addition to lighting, telephone, and signal systems. Lighting was installed along the roadway approaching the tunnel portals.

A total of 4.5 miles (7.2 km) of tunnel were bored through the seven mountains. The seven tunnels were Laurel Hill Tunnel, Allegheny Mountain Tunnel, Rays Hill Tunnel, Sideling Hill Tunnel, Tuscarora Mountain Tunnel, Kittatinny Mountain Tunnel, and Blue Mountain Tunnel. With this, the road became known as the "tunnel highway."

Many designs of bridges were used to carry roads over the tollway, including the concrete arch bridge, the through plate girder bridge, and the concrete T-beam bridge. Various designs of bridges were also used to carry the turnpike over other roads and streams, such as a concrete arch viaduct that was built in New Stanton. At 600 feet (180 m), the New Stanton viaduct was the longest bridge along the original section of the roadway. Other bridges carrying the turnpike were built including the plate girder bridge, such as the bridge over Dunnings Creek in the Bedford Narrows. Smaller concrete T-beam bridges were also built. A total of 307 bridges were constructed along the original section of the turnpike.

Eleven interchanges were built along the turnpike, most of which were trumpet interchanges, where all the ramps merged and reached the toll booths. Only the interchanges at New Stanton, Carlisle, and Middlesex did not follow this design. Lighting was installed approaching interchanges. Acceleration and deceleration lanes were also built. The road also featured guardrails consisting of steel panels attached to I-beams. Large exit signs were used and road signs had cat's-eye reflectors to increase visibility at night. Billboards were banned along the turnpike. In September 1940, the Pennsylvania Public Utility Commission determined that trucks and buses would be allowed to use the highway.

Prior to groundbreaking of the first section, the turnpike commission sent workers out to assess the former railroad tunnels in 1937. In September of that year, a contract was awarded to drain the water out of the tunnels. Following this, workers cleared rockslides and vegetation from the tunnel portals before they could evaluate the condition of the nine tunnels. From the evaluations, the turnpike concluded six of the nine tunnels of the former South Pennsylvania Railroad could be used for the roadway. The Allegheny Mountain Tunnel was in too poor condition to use, while the Quemahoning Tunnel and the Negro Mountain Tunnel were to be bypassed with rock cuts through the mountains. The Quemahoning Tunnel had been completed and used by the Pittsburgh, Westmoreland and Somerset Railroad.

Groundbreaking for the Pennsylvania Turnpike occurred on October 27, 1938 near Carlisle; commission chairman Walter A. Jones dug the first shovel into to earth. The construction of the turnpike was on a tight schedule as completion of the road originally planned by May 1, 1940. After groundbreaking, contracts were awarded for various work in building the road, such as finishing the tunnels of the former South Pennsylvania Railroad, grading the turnpike's right-of-way, construction of bridges, and paving operations. By July 1939, the entire length of the turnpike was under contract.

The first work to begin on the road was grading its right-of-way, which involved a lot of earthwork because of mountainous terrain. Building the highway required the acquisition of several homes, farms, and a coal mine through eminent domain. A tunnel was originally planned across Clear Ridge near Everett, but the turnpike commission decided to build a cut into the ridge. Building the cut involved bulldozers excavating the mountain and explosives being used to blast the rock. Concrete culverts were built to carry streams and roads under the road in the valley floor. The Clear Ridge cut was 153 feet (47 m) deep, the deepest highway cut at that time, and was known as "Little Panama" in reference to the Panama Canal. West of Clear Ridge, cuts and fills were built for the turnpike to pass along the southern edge of Earlston.

A lot of work was also involved on building the roadway up the 3% grade on the eastern end of Allegheny Mountain, which was the steepest grade the turnpike traversed. The base of Evitts Mountain was blasted in order to carry the turnpike across Bedford Narrows along with US 30, the Raystown Branch Juniata River, and a Pennsylvania Railroad branch line. In New Baltimore, the turnpike commission had to purchase land from St. John's Church, which contained a cemetery. As part of the deal, stairways were built on either side of the turnpike to provide access to the church.

Paving operations began on August 31, 1939. The roadway was to have a concrete surface; concrete was poured directly onto the earth without a gravel surface in between. Concrete batch plants were set up along the road to aid in the paving. Interchange ramps, on the other hand, were paved with asphalt. These paving operations led to a delay in the projected opening of the highway and by October 1939 the completion data had been pushed back from May 1 to June 29, 1940 as paving would not take place during the winter of 1939–1940. The commission rushed along with the paving and attempted to increase paving from 1 mile (1.6 km) a day to 5 miles (8.0 km) a day.

Completion was later pushed back to July 4 before being pushed further back to the later part of summer 1940 after rains delayed paving operations. Paving operations would conclude by the end of the summer, and on September 30 the turnpike commission announced the road would open on October 1, 1940. The opening was announced on short notice; no ribbon cutting ceremony was held.

On August 26, 1940, a preview of the highway was organized by commission chairman Jones. It began the prior night with a banquet at The Hotel Hershey and proceeded west along the turnpike, stopping to take a look at Clear Ridge Cut before having lunch at the Midway service plaza. The preview ended with dinner and entertainment at the Duquesne Club in Pittsburgh. That same month, a military motorcade traveled along portions of the turnpike.

The roadway took 770,000 short tons (700,000 t) of sand, 1,200,000 short tons (1,100,000 t) of stone, 50,000 short tons (45,000 t) of steel, and more than 300,000 short tons (270,000 t) of cement to complete. It was built at a cost of $370,000 per mile ($230,910 per km). A total of 18,000 men worked on building the turnpike, with 19 fatalities during construction.

The Pennsylvania Turnpike opened at midnight on October 1, 1940 between Irwin and Carlisle. The day before the opening, numerous motorists lined up at the Irwin and Carlisle interchanges leading to the turnpike. Homer D. Romberger, a feed and tallow driver from Carlisle, became the first motorist to enter the turnpike at Carlisle while Carl A. Boe of McKeesport became the first motorist to enter the turnpike at Irwin. Boe was flagged down by Frank Lorey and Dick Gangle, who became the first hitchhikers along the turnpike. On October 6, the first Sunday following the turnpike's opening, traffic was heavy, with congestion at the toll plazas, tunnels, and service plazas.

In the first 15 days of operation, the road saw over 150,000 vehicles. During its first year, the road earned $3 million in revenue with 5 million motorists using the road. This revenue exceeded the $2.67 million that was needed to pay for operating the roadway and bonds. With the onset of World War II, revenue declined due to tire and gas rationing. Following the war, traffic on the highway increased again.

When it opened, the turnpike became the first long-distance limited-access road in the United States. It provided a direct link between the Mid-Atlantic and Midwestern states and cut down travel time between Pittsburgh and Harrisburg from nearly 6 hours to about 2.5 hours. The road gained the nicknames "dream highway" and "The World's Greatest Highway" from the turnpike commission. The tollway also become known as "The Granddaddy of the Pikes." Postcards and other souvenirs promoted the original stretch's seven tunnels through Pennsylvania's Appalachian Mountains.

The highway was called a "yardstick" by which construction of limited-access highways would be measured. Commission chairman Jones called for more limited-access roads to be built across the country for defense purposes. The turnpike was to serve as a model for a proposed national network of highways planned during World War II. The Pennsylvania Turnpike led to the construction of other toll roads such as the New Jersey Turnpike and eventually the Interstate Highway System. It has been designated a National Civil Engineering Landmark by the American Society of Civil Engineers.

The concrete pavement of the highway started failing a few years after the road opened due to the transverse joints being spaced too far apart and the lack of a gravel layer between the ground and the concrete. As a result, a project began in 1954 to repave the turnpike with a 3-inch (7.6 cm) layer of asphalt between Irwin and Carlisle, which was completed in 1962.

Before the first section of the Pennsylvania Turnpike opened, the commission looked into extending the turnpike east to Philadelphia, primarily for defense purposes. In 1939, the state legislature passed a bill allowing for an extension to Philadelphia, which was signed into law by Governor Arthur H. James in 1940 as Act 11. The extension was projected to cost between $50 and $60 million in 1941. Funding was in place in 1948 for the Philadelphia extension to be built. In July 1948, the turnpike commission offered $134 million in bonds to pay for the extension, which was projected to cost $87 million. The Philadelphia extension was to run from Carlisle east to US 202 in King of Prussia. From there, the extension would connect to a state-maintained freeway that would continue to Center City Philadelphia. Groundbreaking for the Philadelphia extension took place on September 28, 1948 in York County. Governor James H. Duff and commission chairman Thomas J. Evans were present at the ceremony.

The extension would look similar to the original section of the turnpike, but would use air-entrained concrete poured onto stone. Transverse joints on the pavement were also spaced closer together at 46 feet (14 m) rather than the 77 feet (23 m) they were on the original portion. As it traveled through less mountainous terrain, the extension did not require as much earthwork as the original section. It did require the construction of large bridges, such as the ones over the Susquehanna River and the Swatara Creek. The Susquehanna River Bridge was constructed with a 4-foot (1.2 m) raised concrete median and no shoulders to save costs. This extension of the turnpike would use the same style of overpasses as used on the original section; the steel deck bridge was also introduced. With the construction of the Philadelphia extension, the Carlisle interchange was closed and the Middlesex interchange with US 11 was realigned to allow for the new extension; it was renamed to the Carlisle interchange.

Completion of the extension was delayed by weather and a cement workers strike; it was to have been finished by October 1, 1950, the tenth anniversary of the opening of the first section. On October 23, 1950, the Philadelphia extension was previewed in a ceremony led by Governor Duff. The extension opened to traffic on November 20, 1950; the governor and chairman Evans cut the ribbon at the Valley Forge mainline toll plaza to the west of King of Prussia.

A western extension to Ohio was also suggested by Governor James in 1941. In June of that year, Act 54 was signed into law to build the extension. In 1949, the turnpike commission began to look into funding for this, which would run from Irwin to the Ohio border near Youngstown, bypassing Pittsburgh to the north. That September, $77 million in bonds were sold for construction of the western extension. Groundbreaking for the extension took place on October 24, 1949. It was scheduled to take place at the Brush Creek viaduct in Irwin with Governor Duff in attendance.

Like the Philadelphia extension, the western extension required the construction of long bridges such as the ones over the Beaver River and the Allegheny River. The overpasses along the road consisted of steel girder bridges and through plate girder bridges. Unlike the other segments, the concrete arch bridge was not used for overpasses, although it was used to carry the turnpike over roads.

On August 7, 1950, the roadway opened between the Irwin and Pittsburgh interchanges. A dedication ceremony was led by Ohio Governor Frank Lausche on November 26, 1951. The extension opened to the Gateway toll plaza near the Ohio border on December 26, 1951. At the time, the highway ended in a cornfield. Traffic followed a temporary ramp onto rural local roads leading into small towns in Ohio until the connecting Ohio Turnpike could be built. On December 1, 1954, the Ohio Turnpike opened.

In 1951, plans were made to extend the turnpike east to New Jersey at the Delaware River to connect with the New Jersey Turnpike. The measure to build the Delaware River extension was approved by Governor John S. Fine in May of that year. A route was announced for the extension in 1952, which would bypass Philadelphia to the north. It would cross the Delaware River on a bridge north of Bristol near Edgely, where it would connect to a branch of the New Jersey Turnpike. That September, the turnpike commission announced $65 million in bonds would be issued to build the project. Work on the Delaware River extension began on November 20, 1952; Governor Fine dug the first shovel into the earth at the groundbreaking.

As a result of building the extension, the Valley Forge mainline toll plaza was located farther east at the junction with the Schuylkill Expressway. The Delaware River extension included a bridge over the Schuylkill River that was built to the same standards as the Susquehanna River Bridge. On August 23, 1954, the Delaware River Extension opened between King of Prussia and US 611 in Willow Grove. The remainder of the road to the Delaware River opened on November 17, 1954.

In April 1954, $233 million in bonds were issued to build the Delaware River Bridge along with the Northeastern Extension. Groundbreaking for the Delaware River Bridge connecting the Pennsylvania Turnpike to the New Jersey Turnpike took place on June 26, 1954 in Florence, New Jersey. The steel arch bridge, which opened to traffic on May 23, 1956, was funded jointly by the Pennsylvania Turnpike Commission and the New Jersey Turnpike Authority. Pennsylvania Governor George M. Leader and New Jersey Governor Robert B. Meyner were present at the opening ceremony. A mainline toll barrier was built to the west of the bridge, marking the eastern end of the ticket system. This bridge was originally six lanes wide and contained no median. A median was later installed and the bridge was reduced to four lanes.

With the construction of the extensions and connecting turnpikes, the highway was envisioned to be a part of a system of toll roads stretching from Maine to Chicago. When the Delaware River Bridge was completed in 1956, a motorist could drive from New York City to Indiana on limited-access toll roads. By 1957, it was possible to drive from New York City to Chicago without coming to a traffic signal.

In August 1957, the Bureau of Public Roads added the roadway to the Interstate Highway System per the recommendations of various state highway departments to include toll roads in the system. I-80 was planned to run along the turnpike from the Ohio border to Harrisburg while I-80S would continue east toward Philadelphia. I-70 was also planned to follow the turnpike between Pittsburgh and Breezewood. At a June 26, 1958 meeting of the Route Numbering Subcommittee on the U.S. Numbered System, it was decided to move the I-80 designation to an alignment further north while the highway between the Ohio border and the Philadelphia area would become I-80S. I-70 was still designated on the turnpike between Pittsburgh and Breezewood. Between King of Prussia and Bristol, the turnpike was designated I-280.

In April 1963, the state of Pennsylvania proposed renumbering I-80S to I-76 and I-280 to I-276. This proposal was due to the fact that the spurs of I-80S did not connect to I-80 in northern Pennsylvania. The renumbering was approved by the Federal Highway Administration on February 26, 1964. With this renumbering, the tollway would carry I-80S between the Ohio border and Pittsburgh, I-76 between Pittsburgh and King of Prussia, I-70 between New Stanton and Breezewood, and I-276 between King of Prussia and Bristol. In 1971, the state of Ohio wanted to eliminate I-80S by replacing it with a realigned I-76. The state of Pennsylvania disagreed with the change and recommended that I-80S become I-376 instead. They later changed its mind and supported Ohio's plan to renumber I-80S as I-76. In December of that year, the change was approved by the American Association of State Highway Officials. As a result, I-76 would follow the highway between the Ohio border and King of Prussia.

As traffic levels increased, bottlenecks at the two-lane tunnels on the Pennsylvania Turnpike became a major issue. By the 1950s, traffic jams formed at the tunnels, especially during the summer. In 1959, four Senators urged for state officials to work with the turnpike commission to study ways to improve the traffic jams at the tunnels. The commission began studies that year on how to resolve the traffic jams at the Laurel Hill and Allegheny Mountain tunnels; studies for the other tunnels followed. At the conclusion of the studies, the turnpike commission planned to make the entire turnpike four lanes by either adding a second tube at the tunnels or bypassing them. The new and upgraded tunnel tubes would feature white tile, fluorescent lighting, and upgraded ventilation.

The turnpike commission announced plans to build a second bore at the Allegheny Mountain Tunnel along with a four-lane bypass of the Laurel Hill Tunnel in 1960. A bypass was planned for the Laurel Hill Tunnel because traffic would be relieved faster and less expensively than it would by boring another tunnel. In 1962, the turnpike commission approved these two projects. That August, $21 million in bonds were sold to finance the two projects.

The Laurel Hill Tunnel was bypassed by way of a deep cut to the north of the tunnel; it would feature a wide median, truck climbing lanes, and a 145-foot (44 m) deep cut into the mountain. Groundbreaking for the new alignment took place on September 6, 1962. This bypass of Laurel Hill Tunnel opened to traffic on October 30, 1964 at a cost of $7.5 million.

Work on boring the second tube at Allegheny Mountain Tunnel also began on September 6, 1962. In building the second tube, the former South Pennsylvania Railroad tunnel was considered, but was again rejected as it was in too poor condition. On March 15, 1965, the new tube opened to traffic. Following the opening of the new tunnel, the original tube would be closed to allow for updates to be made, reopening on August 25, 1966. The construction of the second tube at Allegheny Mountain cost $12 million.

In 1965, the turnpike commission announced plans to build second tubes at the Tuscarora, Kittatinny, and Blue Mountain tunnels while a 13.5-mile (21.7 km) bypass of the Rays Hill and Sideling Hill tunnels would be built. A study in the early 1960s had concluded that a bypass would be the best option to handle traffic at Rays Hill and Sideling Hill. A bypass of these two tunnels was considered in the 1930s, but at the time was determined to be too expensive. The turnpike commission sold $77.5 million in bonds in January 1966 to finance this project.

Construction of the bypass of the Rays Hill and Sideling Hill tunnels involved building a cut across both Rays Hill and Sideling Hill. The new alignment began at the Breezewood interchange, where a portion of the original turnpike was used to access US 30. In building the cut across Rays Hill, a portion of US 30 had to be realigned. The cut over Sideling Hill passes over the Sideling Hill Tunnel. The new alignment ends a short distance east of the Cove Valley service plaza on the original segment. This bypass of the two tunnels would have a 36-foot (11 m) wide median with a steel barrier in the middle. The turnpike bypass of Rays Hill and Sideling Hill tunnels opened to traffic on November 26, 1968.

Meanwhile, studies concluded that a parallel tunnel was the most economical option at the Tuscarora, Kittatinny, and Blue Mountain tunnels. Work on the new tube at the Tuscarora Mountain Tunnel began on April 11, 1966 while construction began at the Kittatinny and Blue Mountain tunnels a week later. The parallel tubes at these three tunnels would open on the same day as the bypass of the Rays Hill and Sideling Hill tunnels;the original tubes were subsequently remodeled. Both the new and remodeled tunnels would have fluorescent lighting, white tile walls, and a lane width of 13 ft (4.0 m). The portals of the new tunnels were designed to resemble the original tunnels. Reconstruction of the original Tuscarora Mountain Tunnel was completed in October 1970 while work on refurbishing the original Kittatinny and Blue Mountain tunnels was finished on March 18, 1971. With the completion of these projects, the entire length of the highway was four lanes wide.

With the completion of these projects, the stretch of the former roadway that passed through the Rays Hill and Sideling Hill tunnels became known as the Abandoned Pennsylvania Turnpike. The turnpike commission continued to maintain the tunnels for a few years, but eventually abandoned them. The abandoned stretch deteriorated, with signs and guardrails removed. Pavement started crumbling and trees grew in the median, with vandals and nature taking over the tunnels. The turnpike commission still performed some maintenance on the abandoned stretch and used it for testing pavement marking equipment. In 2001, the turnpike commission turned over a significant portion of the abandoned section to the Southern Alleghenies Conservancy, with bicycles and hikers able to use the former roadway. The abandoned stretch of the turnpike is the longest stretch of abandoned freeway in the United States.

The median of the roadway, while initially thought to be wide enough, was viewed as being too narrow by 1960. As a result, the turnpike commission had installed median barriers at curves and high-accident areas starting in the 1950s. In 1960, they began a project to install 100 miles (160 km) of median barrier along the turnpike. Work on the median barrier was completed in December 1965 at a cost of $5 million.

In October 1963, work began on replacing the New Stanton interchange, which required left turns across traffic on the ramps and was frequently congested. The new grade-separated interchange opened on November 12, 1964 and provided access to I-70. A new interchange opened at Harrisburg East in 1969 that served I-283 and PA 283. Due to the realignment of US 222 to a four-lane freeway, a new Reading interchange was proposed. The new interchange opened on April 10, 1974.

In 1969, the turnpike commission said that due to increasing traffic, it was necessary to widen the turnpike. They proposed doubling the number of lanes from four to eight; the portion in the Philadelphia area was to be ten lanes wide. Cars and trucks would be carried on separate roadways under this plan. The roadway would also have an 80 mph (130 km/h) speed limit and holographic road signs. This widening would have kept much of the routing intact, but significant realignments were proposed between the Allegheny Mountain and Blue Mountain tunnels. Due to the $1.1 billion cost and the 1973 oil crisis that resulted in a 55 miles per hour (89 km/h) speed limit being implemented, this would not be implemented.

By the 1970s, the Pennsylvania Turnpike started to see a decline in traffic due to the opening of I-80, which provided a shorter route across the northern part of the state, and the 1973 oil crisis, which led to a decline in long-distance travel. In the late 1970s, the turnpike commission proposed truck climbing lanes east of the Allegheny Mountain Tunnel, near Donegal, and near the Laurel Hill Bypass. These truck climbing lanes were completed on December 2, 1981.

The portion of the turnpike in the Philadelphia area had become a congested commu