Interstate 93 begins in the south at exit 12 of I-95 in Canton, Massachusetts. I-93 begins co-signed with U.S. Route 1 North. At this junction, I-95 North heads to the northwest (co-signed with U.S. Route 1 South, as well as Route 128, which begins at the interchange). to serve as the beltway around Boston, while I-95 South runs by itself southwest through Boston's southeastern suburbs towards Rhode Island.
The first few miles of I-93 run almost due east through Boston's southern suburbs, passing through Canton and Randolph. In Randolph, I-93 meets the northern end of Route 24 (Fall River Expressway/AMVETS Memorial Highway) at Exit 4. I-93 continues east into Braintree, interchanging with Route 3, the major freeway linking Boston to Cape Cod, at Exit 7. Route 3 North joins I-93 and US-1, and the highway turns north towards Boston.
Signs in the Financial District of Boston, Massachusetts point towards Downtown Crossing, Chinatown, Interstate 93, and Interstate 90.Upon turning northward, the highway is known as the Southeast Expressway before reaching the city itself. Upon entering the city, the highway is known as the Central Artery, and passes beneath downtown Boston. A major intersection with the Massachusetts Turnpike/Interstate 90 (Exit 20) takes place just south of downtown Boston. After the massive interchange, motorists use the Thomas P. O'Neill Jr. Tunnel to travel underneath the city and then use Zakim Bunker Hill Bridge to cross the Charles River. Two exits are located in the tunnel, where the speed limit is a mere 45 miles an hour. Route 3 leaves the Artery just before the Zakim bridge via Exit 26, and U.S. Route 1 leaves the Artery just after the bridge, via Exit 27 (no southbound access). From Boston through the rest of Massachusetts, Concord appears as the control city on northbound overhead signs. The Artery ends as I-93 continues north out of the city.
I-93 continues through the northern suburbs of Boston, coming to a second intersection with Interstate 95. Bostonians traveling north can either change over to I-95 north to eventually reach Maine, or remain on I-93 towards New Hampshire. Farther north, in Andover, I-93 meets I-495, providing access to Worcester to the southwest and New Hampshire's seacoast region to the northeast. Just south of the state line, I-93 crosses the Merrimack River into Methuen, where it interchanges with Route 213, a connector between I-93 and I-495. I-93 then crosses into New Hampshire.
In all, I-93 has 48 numbered exits in Massachusetts, although several numbers are skipped in and near Boston. Exit 48 in Methuen, just before the New Hampshire state line, is the highest-numbered exit along the entire route. Due to the highway being one of the two major Interstates that enter Boston directly (Interstate 90 is the other), nearly the entire length of the highway in Massachusetts carries four lanes in each direction and is almost always very busy.
Interstate 93 travels just over 131 miles in the Granite State; around 2/3 of the highway's total distance. Serving as the main interstate route in New Hampshire, it connects nearly every major city and town in the state, including both the state capital, Concord, and its largest city, Manchester. Beyond Concord are the towns of Tilton, Plymouth, and Littleton.
Between the northern end of I-293 in Hooksett and the beginning of I-89 in Bow, I-93 also carries the northern end of the Everett Turnpike. There is one toll booth along this section, at Exit 11 in Hooksett; toll for passenger cars is currently $1 (75бщ at the ramp toll booth). This is the only toll collected along the entire length of Interstate 93. I-93 in New Hampshire is also notable for having state liquor stores serve as rest areas, which are passed just after the toll plaza, traveling north. There are separate stores on both sides of the Interstate for travelers in each direction.
I-93 enters New Hampshire at Salem, where the current reconstruction of the Exit 1 ramps (leading to the Mall at Rockingham Park) along with the reduction of the freeway from 4 northbound lanes to only 2 tends to cause traffic backups. A rest area/welcome center is available on the northbound side of the freeway, directly before Exit 1. I-93 remains only 2 lanes wide in each direction for its first 18 miles, until the split with Interstate 293 and the junction with New Hampshire Route 101 add a third lane back to the freeway. I-93 and New Hampshire Route 101 run concurrently for about a mile before New Hampshire Route 101 heads directly east as its own freeway, serving Portsmouth and the Seacoast region. I-93 keeps three lanes of traffic until the junction with Interstate 89, when it reduces back to two, and remains a two-lane freeway through the rest of its journey northward.
It crosses the Merrimack River again before going through the state capital of Concord. In Concord, Interstate 393 heads directly east (co-signed with eastbound U.S. Route 4 and U.S. Route 202), providing another route to the Seacoast region. Westbound U.S. Route 4 joins I-93 and runs concurrently with it until Exit 17 for Penacook, about 5 miles further north, before exiting westward. Continuing north, I-93 traverses the Lake Winnipesaukee tourist region and makes its way north through the heart of the White Mountains Region. I-93 passes through Franconia Notch State Park as a Super-2 parkway, the only instance of a two-lane Interstate highway in the United States. This stretch carries a 45 mile per hour speed limit. For the trip through Franconia Notch, I-93 and U.S. Route 3 run concurrently.
Beyond Franconia Notch State Park, U.S. Route 3 heads northeastward through the Great North Woods region, while I-93 runs to the northwest. The final town along I-93 in New Hampshire is Littleton, served by three exits. Many motorist services are available at Exit 42. After passing through town, it crosses the Connecticut River into Vermont. The last exit along I-93 is exit 44 for Monroe, through which a rest area/welcome center is accessible to travelers on both sides of the highway.