Interstate 95 in Massachusetts

To continue on I-95 northbound, motorists must make a sharp clockwise curve at exit 26 (old exit 12) in Canton.

I-95 crosses the state border from Pawtucket, Rhode Island, into Attleboro as a six-lane highway, with the first northbound exits, 2A and 2B, providing access to Route 1A and nearby US 1 near the border. (There is an exit 1, but it is a southbound-only exit connecting to US 1 south into Rhode Island). Exits 4–7 (old exits 3–5) also serve the Attleboro area, with exit 6 (old exit 4) at the northern terminus of I-295.

Exits 12A and 12B (old exits 6A and 6B) in Mansfield provide access to I-495, the "outer circumferential" beltway around Greater Boston. I-495 provides northbound connections to Worcester, the Massachusetts Turnpike, and the western part of the state, and southbound connections to Cape Cod. Mansfield is home to the Xfinity Center, a Live Nation Entertainment-owned amphitheater that hosts numerous concert events, and TPC Boston, a PGA Tour player's club that hosted the Dell Technologies Championship yearly. The two venues are located near I-95's interchanges with Route 140.

I-95 continues northward into Foxborough, home of Gillette Stadium, located on US 1 and accessible from exit 19 (old exit 9). As the Interstate continues through Sharon, it then enters Greater Boston and the towns of Walpole, and Norwood, before entering Canton, where it meets I-93 at its southern terminus, and I-93 continues as exit 26 (old exit 12) to the right of I-95, while I-95 traffic is routed in a single lane to a sharp clockwise curve where it meets US 1 in a wrong-way concurrency.

Upon interchanging with I-93, I-95 loops around to the west, taking over the roadbed from I-93 (now four lanes) and joining US 1 southbound in a wrong-way concurrency. Route 128 begins here as well. The highway enters Westwood next, with US 1 leaving the freeway near the Dedham town line to parallel I-95 back to the south. I-95 and Route 128 makes its way around Greater Boston, passing through Dedham, Needham, and Wellesley, where the freeway has an interchange with Route 9, and the freeway widens to eight lanes. Then, the highway passes through Newton, then enters Weston and has a large interchange with the Massachusetts Turnpike (I-90) that provides connections to nearby Route 30. With the exception of between the I-90 on- and offramps, this portion of I-95 is four lanes in each direction.

I-95 and Route 128 are due west of Boston at this point and begin to turn to the northeast, serving the city of Waltham and the town of Lexington along the way. The freeway has an interchange with Route 2 (Concord Turnpike) at exit 45 (old exit 29). Upon entering the town of Burlington, I-95 and Route 128 have an interchange with US 3, the Northwestern Expressway, at exit 50A (old exit 32A). US 3 provides a direct freeway connection with the Lowell–Nashua, New Hampshire, metro area. Access to the Middlesex Turnpike and Burlington retail district is facilitated at this interchange as well. US 3 south briefly joins the freeway in another wrong-way multiplex in order to connect with its old alignment, leaving at exit 51A (old exit 33A). I-95 and Route 128 continue northeast through the city of Woburn and into Reading.

In Reading, I-95 and Route 128 once again have an interchange with I-93. After crossing I-93, the now six-lane highway continues to the northeast, serving the towns of Wakefield, Lynnfield, and Lynn before crossing into Peabody, where Route 128 leaves I-95 at exit 64 (old exit 45) via the three left-most lanes as its own freeway toward Gloucester, while I-95 continues as the two right-most lanes in a somewhat sharp counterclockwise (albeit the fact that it contains two lanes) loop.

After leaving Route 128, I-95 expands back to six lanes and then to eight lanes at the partial interchange with US 1 (exit 66, old exit 46) about one mile (1.6 km) north of Route 128 and heads north through the less densely populated northeastern portion of the state. The freeway serves the communities of Danvers, Boxford, Topsfield, Georgetown, Rowley, Newbury, West Newbury, Newburyport, Amesbury, and Salisbury. Traffic density is generally low on this 25-mile (40 km) stretch of freeway.

I-495 has its northern terminus at I-95 exit 89 (old exit 59) just south of the New Hampshire state line, a Y interchange that merges I-495 onto I-95. Northbound access to I-495 south is possible via exit 58 for Route 110 westbound, which leads to I-495's exit 119 (old exit 55) (I-495's last northbound exit before I-95). The northernmost exit in Massachusetts is exit 90 (old exit 60), providing access to Main Street toward Amesbury and Route 286 toward Salisbury Beach and Hampton Beach (the southbound ramp starts in New Hampshire). After crossing underneath the connecting roads, I-95 crosses the state line into Seabrook, New Hampshire.

This is a list of rest areas on I-95 in Massachusetts.

• Mansfield Rest Area (milepost 10): It is Northbound only between exits 7, 12A, and 12B (old exits 5, 6A, and 6B) and has portable restrooms, phones, and a picnic area.
• North Attleborough Parking Area (milepost 10): It is southbound only between exits 12A, 12B, and 7 (old exits 6 and 5) and has a parking area and phones.
• Westwood Rest Area (milepost 29): It is southbound only between exits 28 and 27 (old exits 14 and 13) and has restrooms, phones, and a picnic area.
• Dedham Truck turnout: It is southbound only between exits 32, 31A, and 31B (old exits 17, 16A, and 16B) and parking only with no facilities.
• Newton Service Plaza: It is southbound only near exit 37 (old exit 21) and has 24-hour food and fuel with McDonald's and Honey Dew Donuts.
• Lexington Service Plaza: It is northbound only near exits 46A–B (old exits 30A–B) and has 24-hour food and fuel with McDonald's, Honey Dew Donuts, and Original Pizza of Boston.
• Massachusetts Visitor Center (milepost 90): It is southbound only at the New Hampshire state line (exit 90, old exit 60) and has tourist information, restrooms, and phones.

Weigh stations are located on the northbound and southbound sides of the highway at the following locations:

• In Attleboro between exits 2 and 4 (old exit 3).
• In Rowley between exits 76A, 76B, and 78 (old exits 53A, 53B, and 54).

Between the Rhode Island state line and I-93 in Canton, and again between the northern end of the beltway and the New Hampshire state line, the speed limit is 65 mph (105 km/h). After leaving Route 128, I-95 expands to eight lanes and heads north through the less densely populated northeastern portion of the state hence why the speed limit increases to 65mph from Peabody to the New Hampshire border crossing through more rural areas in northeastern Massachusetts, including Georgetown, Massachusetts, Rowley, Massachusetts, Newbury, Massachusetts and others in Salisbury. The sharp transition curve from I-95 north onto the Route 128 beltway in Canton is posted for 25 mph (40 km/h). Along the beltway, the speed limit is 55 mph (89 km/h), and the speed limit on the transition ramps at exit 64 (old exit 45) at the I-95/Route 128 split in Peabody is 45 mph (72 km/h) northbound and 50 mph (80 km/h) before increasing to 65mph from that point on until it reaches the New Hampshire border in Salisbury, Massachusetts.

The $315-million (equivalent to $380 million in 2021[5]) MassDOT Highway Division project widened the 14.3-mile (23.0 km), six-lane section of highway to eight lanes from north of Route 9 in Wellesley to Route 24 in Randolph. The project consisted of adding a lane on the inside of each carriageway, complete with a 10-foot (3.0 m) inside shoulder. The existing 1950s bridges, 22 in total, were replaced. The project included construction of a new two-lane ramp from Route 128 to I-95 in Canton and installation of a new interchange at Kendrick Street in Needham, designated as exit 35A (old exit 19A) with the ramps to Highland Avenue as exits 35B–C (old exits 19B–C).

During the initial construction of I-95, a provision had already been made for a fourth lane within the widely spaced median along the 1.5-mile (2.4 km) length of I-95 running from just north of the US 1 interchange in Dedham northwestward to the Route 109 interchange, and this will finally be used for the Add-A-Lane project.

Construction on phase 1 was officially completed in October 2009. Construction of phase 2 of the project began in mid-2006. This phase of the project consisted of the replacement of the US 1 and Route 1A bridges over I-95 in Dedham along with the road widening between exits 27, 29A, and 29B (old exits 13, 15A, and 15B). Construction of four sound barriers between the US 1 and I-93 interchanges were also included. This phase was completed in early 2011.