Route 2 is a major east–west state highway in Massachusetts, parts of which are sometimes known as the Cambridge and Concord Turnpike. Along with Route 9 and U.S. Route 20 to the south, these highways are the main alternatives to the Massachusetts Turnpike/I-90 toll highway. Route 2 runs the entire length of the northern tier of Massachusetts, beginning at the New York border, where it connects with New York State Route 2, and ending near Boston Common in Boston.

Route 2 proceeds east from the New York state line on a winding, scenic path in Williamstown. It serves the Williams College area and North Adams. East of North Adams, Route 2 ascends via a hairpin turn into the Berkshire Mountains along the old Mohawk Trail.

It then goes from Berkshire County into Franklin County, Massachusetts, running into Interstate 91 at an interchange in Greenfield and briefly runs concurrent with the interstate highway. At this point the old Route 2 becomes Route 2A and goes through downtown Greenfield. Route 2, however, exits off I-91, becoming an expressway briefly before becoming a two-lane freeway. Outside of Greenfield, Route 2A temporarily ends and merges with Route 2. Route 2 then becomes a regular two-lane surface road in Gill and through Erving though it has some grade-separated interchanges in Millers Falls at its intersection with Route 63. There is another gap in the two-lane expressway in the Erving area. Recently, the road in Erving was routed to the north and straightened to avoid the paper mill next to the river. This rerouting led to the road being shortened by less than a tenth of a mile.

Once the road enters the Town of Orange, Route 2A resumes and breaks off Route 2. At this point Route 2 again becomes a two-lane expressway. In Orange, Route 2 runs concurrent with U.S. Route 202. The road at this point enters the town of Athol in Worcester County, Massachusetts. After its eastern interchange in Phillipston when US 202 breaks off to the north, Route 2 becomes a full four-lane expressway, though not to Interstate standards in most points. It continues through Gardner and Leominster, where Interstate 190 begins, heading south to Worcester. In Fitchburg, Route 2 has several at-grade intersections with Oak Hill Road, Palmer Road, Mt. Elam Road, and Abbott Avenue. At the intersection with Mt. Elam Road, a traffic light remains in use on the eastbound side.

Route 2 continues east to Middlesex County, Massachusetts. At this point it enters Boston's outer loop at the interchange with Interstate 495 in Littleton. It continues as an expressway until it goes into Acton, where it runs into Piper Road and Taylor Road at a traffic light (Exit 44). At this point the expressway ends and Route 2 becomes a regular divided highway at most points and just a four-lane highway at other points. At the Concord Rotary, a major traffic choke point, Route 2 intersects with Route 2A and the beginning of Route 119 (which is overlapped with 2A at that point). After the rotary the road loses its dividing wall as it passes past the State Police (who have an emergency-only traffic light) and over the Assabet River. Route 2A used to then break away from Route 2 at the next traffic light to go left into Concord but is now overlaid with Route 2. At Crosby's Corner, the sixth intersection after the rotary, Route 2A goes straight while Route 2 veers right (but still heads east). The highway loses its dividing wall until the Bedford St intersection in Lincoln where it becomes divided again. MassHighway currently expects to rebuild the Crosby Corner intersection and create a dividing wall from there to Bedford St in 2011-2013.

At this point Route 2 enters Lexington and still is a divided 4-lane road with surface intersections. It then heads to Boston's inner belt, crossing Interstate 95/Route 128. From there, Route 2 is a six-lane and then eight-lane limited access highway until Exit 60, where it narrows with little warning to six lanes and then to four lanes. This section of expressway actually meets the standards of an interstate highway. The final off-ramp leads directly to the large parking garage at the MBTA Alewife Station. At this point the road heads into Cambridge, Massachusetts.

The limited access highway portion ends at a signalized intersection, where it merges with U.S. Route 3 south and Route 16 west in Cambridge and continues as a four-lane surface road to the Boston Public Garden. Route 2 follows Alewife Brook Parkway, Fresh Pond Parkway, Gerry's Landing Road, and Memorial Drive (all parkways maintained by the Department of Conservation and Recreation) through Cambridge. It crosses into Boston on the Boston University Bridge. After crossing Commonwealth Avenue (U.S. Route 20), it follows Montfort Street and Beacon Street into Kenmore Square which is the eastern terminus of US Route 20. From Kenmore Square, Route 2 follows Commonwealth Avenue to Arlington Street. It circles the Public Garden in Boston, using Arlington Street to Boylston Street to Charles Street. Route 2 ends at Route 28 at the intersection of Charles Street and Beacon Street between Boston Common and the Boston Public Garden.

In the early 1920s, Route 2 was known as New England Interstate Route 7 (NE-7), a major road connecting Boston with Troy, New York. NE-7 ran roughly where Route 2A (the original surface alignment of Route 2) does now except near the New York state line. NE-7 used current Massachusetts Route 43, New York State Route 43 and New York State Route 66 to reach Troy. Current Route 2 from Williamstown to Petersburgh was previously numbered as Route 96.

Route 2 connected as a highway in its current right-of-way at Alewife Brook Parkway at some point before 1937.

An upgraded Route 2 was originally planned to continue as Boston's Northwest Expressway (merging with a re-routed U.S. Route 3 at the Arlington-Lexington or Arlington-Cambridge border) to a junction with Interstate 695, the Inner Beltway, but this, along with the Inner Beltway itself, was cancelled in 1970, accounting for the abrupt narrowing at Alewife. In place of the highway project, the MBTA Red Line was extended from Harvard to Alewife in the 1980s.

This major project has been planned since 1999. The intersection has an average of 90 accidents a year. The project will solve the traffic and safety problems at the very dangerous Crosby's Corner intersection (junction of Route 2 and 2A) in Concord. The project, expected to cost $71.9 million, will widen Route 2 from Bedford Road in Lincoln to 300 feet west of Sandy Pond Road in Concord. The project will eliminate the at grade intersection and realign it and construct new entrance and exit ramps along with constructing new service roads next to Route 2. The project was expected to begin in 2011. The state has recently spent $25-35 million for property takings in the path of the new alignment of Route 2. In January 2010 a speeding tanker truck carrying liquid asphalt flipped over on Route 2 and crushed three cars. The truck driver was med-flighted to a Boston hospital with serious injuries. The highway was shut down for five hours causing traffic delays for the 46,000 commuters daily. The accident put the spotlight back on the Crosby's Corner project.

The full project includes building a new overpass bridge over Route 2 and building multiple service roads next to Route 2. Fourteen retaining walls will be built to accommodate the new interchange ramp construction. Work also consists of a new signalized intersection. The project was put out to bid for contractors on September 19, 2011. A contractor was expected to be chosen over the winter and construction was expected to begin in Spring 2012 on the estimated $55 million project.

The Army Corps of Engineers published a notice for this project, because of its impact on wetlands at Crosby's Corner. During the summer of 2012, activity on this portion of Route 2 included surveying and the installation of orange painted stakes. Signs were added in January 2013 indicating that construction would start on January 14.

Westbound in Shelburne

Eastbound at Whitcomb Summit in Florida