Route 2 is a 142.29-mile-long (228.99 km) major east–west state highway in Massachusetts, United States. 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. Older alignments of Route 2 are known as Route 2A.

Route 2 proceeds east from the New York state line on a winding, scenic path in Berkshire County through Williamstown, where it serves the Williams College area, and through North Adams, where it serves the Massachusetts College of Liberal Arts. East of North Adams, Route 2 ascends via a hairpin turn into the Hoosac Range along what is known as the Mohawk Trail.

Route 2 then enters Franklin County, meeting Interstate 91 at an interchange in Greenfield and briefly runs concurrently with I-91. While the old Route 2 becomes Route 2A and goes through downtown Greenfield, Route 2 joins I-91 in a short concurrency before leaving it and becoming a two-lane freeway. Outside Greenfield, Route 2A temporarily ends and merges with Route 2, and Route 2’s freeway section ends. Route 2 remains a two-lane surface road in Gill and Millers Falls (though it does have an interchange with Route 63). 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 one-tenth of a mile.

As the route approaches Orange, Route 2A resumes and diverges from Route 2. At this point, Route 2 again becomes a two-lane freeway. In Orange, Route 2 runs concurrently with U.S. Route 202. The road at this point enters the town of Athol in Worcester County. After its eastern interchange in Phillipston when US-202 departs to the north, Route 2 becomes a four-lane freeway, though not to Interstate standards at most points. It continues through Gardner into Fitchburg where Route 2 has several at-grade intersections with Oak Hill Rd, Palmer Rd, Mt. Elam Rd and Abbott Ave. At the intersection with Mt. Elam Rd, a traffic light remains in use on the eastbound side. Continuing east into Leominster, Interstate 190 splits off, heading south to Worcester.

Route 2 continues east to Middlesex County and enters Boston's outer loop at the interchange with Interstate 495 in Littleton. It continues into Acton, where Route 2 reduces its speed to 45 miles per hour, and becomes a four-lane expressway with at-grade intersections. At the Concord Rotary, a major traffic choke point, Route 2 becomes a four-lane surface road and intersects with Route 2A and the eastern terminus of Route 119 (which is concurrent with Route 2A). After the rotary, the road passes by the State Police (who have an emergency-only traffic light) and over the Assabet River. Route 2A formerly broke away from Route 2 at the next traffic light to go left into Concord but is now overlaid with Route 2, where it becomes a four-lane expressway again. At Crosby's Corner, the sixth intersection after the rotary, Route 2A exits under the highway while Route 2 veers right (but still heads east). After a signalized at-grade intersection with Bedford Road in Lincoln, the highway becomes a four-lane arterial road.

Route 2 enters Lexington and heads to Boston's inner belt, and as it crosses Interstate 95/Route 128, it becomes a six-lane freeway with a speed limit of 55 miles per hour. In Belmont, Route 2 remains a six-lane freeway, and then becomes an eight-lane freeway at Exit 132 (formerly 57) in Arlington, where U.S. Route 3 would have joined it from the north. At Exit 135 (formerly 60), the freeway narrows in width to six lanes. The section of freeway from Route 128 to the Cambridge line meets the standards of an interstate highway. The highway enters Cambridge, the highway reduces its speed limit back to 45 miles per hour and becomes a five-lane freeway (three lanes heading east, two lanes heading west), with a strip of residential and transit-oriented development on its eastbound side, including an off-ramp that serves the MBTA Alewife Station, Cambridge Discovery Park and development to the south and west of the station. After the Alewife exit, the highway narrows again to four lanes.

The highway then meets a large at-grade intersection with Routes 3 and 16, where Route 2 east merges with U.S. Route 3 south and Route 16 and continues as a four-lane, 35 mile per hour arterial road — managed by the Department of Conservation and Recreation — for the rest of its time in Cambridge. Route 2 follows Alewife Brook Parkway and Fresh Pond Parkway along its wrong way concurrency with Routes 3 and 16, before Route 16 heads west into Watertown. Route 2 and Route 3 concurrently start paralleling the Charles River as Memorial Drive, passing by Harvard University’s campus. It then heads southward on the Boston University Bridge into Boston proper, as it separates from Route 3. It winds through the Boston University campus as Mountfort Street and crosses over both the Massachusetts Turnpike and Commonwealth Avenue before heading due east towards Kenmore Square, while running parallel to U.S. Route 20. Immediately east of the Boston University campus, it crosses into Kenmore Square, which is also the eastern terminus of U.S. Route 20. From Kenmore Square, Route 2 follows Commonwealth Ave to Arlington St. It circles the Boston Public Garden, using Arlington, Boylston, and Charles Streets. Route 2 east goes along northbound Route 28 north at the intersection of Charles and Beacon Streets between Boston Common and the Boston Public Garden. As Route 28 north joins Storrow Drive, which shortly after would join Route 3, Route 28 south joins Route 2 and completes the loop around Boston Public Garden.

The route amalgamates and supersedes various named highways in some cases going back to the pre-automobile era. For example, parts of Route 2 are sometimes known as the Cambridge and Concord Turnpike and the Mohawk Trail.

In the early 1920s, Route 2 was known as New England Interstate Route 7 (NE-7), a major road in the New England road marking system 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.

The Leominster to Ayer section opened on July 3, 1953, completing the expressway portion from Westminster to West Concord. Full grade separation between Route 128 and Alewife Brook Parkway was completed around 1970.

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This major project has been planned since 1999. The intersection had an average of 90 accidents a year. The project was intended to solve the traffic and safety problems that had long occurred at the Crosby's Corner intersection (junction of Route 2 and 2A) in Concord. The project, which was expected to cost $71.9 million, widened Route 2 from Bedford Rd in Lincoln to 300 feet west of Sandy Pond Rd in Concord. The project eliminated the at grade intersection, realigned Route 2, and constructed new entrance and exit ramps along with new service roads next to Route 2.

The full project included building a new overpass bridge over Route 2 and building multiple service roads next to Route 2. Work also consisted 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. As of April 2014 the project was underway and predicted completion was spring 2016. The project was completed in 2016, with a large improvement in traffic flow.

A project to improve the Concord Rotary, at the convergence of Route 2, Route 2A/119 (Elm Street), Barrett's Mill Road and Commonwealth Avenue, has been in planning since 2003 or even earlier. More than 61,000 cars use this rotary on a typical day, and the backed up traffic can be significant. The improved intersection would include overpasses for local streets, while Route 2 traffic would continue unimpeded at grade. However, the project was removed from the funded portion of the Boston Region Metropolitan Planning Organization's (MPO) Long Range Transportation Plan (LRTP) in August 2009 and is currently on hold.

MassDOT was scheduled to replace the old sequential exit numbers with the new milepost-based exit numbers beginning in summer 2020, which had been delayed since 2016. On March 16, 2021, MassDOT announced that the Route 2 exit numbers would get renumbered for four weeks starting on March 23.

County	Location	mi	km	Old exit	New exit	Destinations	Notes
Berkshire	Williamstown	0.000	0.000			NY 2 west – Troy, NY	Continuation into New York
		3.824	6.154			US 7 south – Pittsfield	Western end of concurrency with US 7
		6.221	10.012			US 7 north – Pownal, VT, Montreal, Que	Eastern end of concurrency with US 7
		6.746	10.857			Route 43 south – Hancock, Stephentown, NY	Northern terminus of Route 43
	North Adams	11.571	18.622			Route 8 south – Adams	Western end of concurrency with Route 8
		11.740	18.894			Route 8A south	Northern terminus of Route 8A "U" segment
		12.405	19.964			Route 8 north – Clarksburg, Stamford, VT	Eastern end of concurrency with Route 8
Franklin	Charlemont	29.807	47.970			Route 8A south – Hawley, Windsor	Western end of concurrency with Route 8A
		30.4	48.9			Route 8A north – Heath, Jacksonville, VT	Eastern end of concurrency with Route 8A
	Buckland	37.390	60.173			Route 2A east – Shelburne Falls	Former western terminus of Route 2A
		37.806	60.843			Route 112 south – Buckland, Ashfield	Western end of concurrency with Route 112
	Shelburne	38.062	61.255			Route 112 north – Shelburne Falls, Colrain	Eastern end of concurrency with Route 112
		38.942	62.671			Route 2A west – Shelburne Falls, Buckland	Former western end of concurrency with Route 2A
	Greenfield	47.398	76.280	Western end of freeway section
				26	43	I-91 south / Route 2A east – Springfield, Greenfield Center	Western end of concurrency with I-91 and Route 2A; western terminus of Route 2A
		50.139	80.691	27	46	I-91 north – Brattleboro, VT	Eastern end of concurrency with I-91; exit number not signed westbound
		50.789	81.737			US 5 / Route 10 – Greenfield, Bernardston
		51.480	82.849	Eastern end of freeway section
		52.242	84.075			Route 2A west – Greenfield Center	Western end of concurrency with Route 2A
	Erving	57.1	91.9			To Route 63 – Northfield, Millers Falls	Access via Gateway Drive
		57.4	92.4			Forest Street to Route 63 – Northfield, Hinsdale, NH
		57.7	92.9			To Route 63 – Millers Falls	Access via Prospect Street
		64.865	104.390			Route 2A east to Route 78 – Orange, Wendell	Eastern end of concurrency with Route 2A
		65.060	104.704	Western end of limited-access section
	Orange	66.571	107.136	14	67	West River Street – Orange, Lake Mattawa
		69.788	112.313	15	70	Route 122 – Orange Ctr, Worcester
		70.676	113.742	16	71	US 202 south / Daniel Shays Highway – Belchertown, Athol	Western end of concurrency with US 202
Worcester	Athol	75.155	120.950	17	75	Route 32 – Athol, Petersham
	Phillipston	76.474	123.073	18	77	Route 2A – Athol, Phillipston
		79.009	127.153	19	79	US 202 north / Route 2A – Baldwinville, Winchendon, Phillipston	Eastern end of concurrency with US 202
	Templeton	81.915	131.829	20	82	Baldwinville Road – Templeton, Baldwinville
		83.459	134.314	21	83	Route 2A / Route 101 – East Templeton, Ashburnham
	Gardner	86.500	139.208	22	86	Route 68 – Gardner, Hubbardston
		87.253	140.420	23	87	Pearson Boulevard – Gardner
	Westminster	89.738	144.419	24	90	Route 140 north / West Main Street – Winchendon, Westminster	Western end of concurrency with Route 140; signed as exits 90A (south) and 90B (north) westbound
		91.764	147.680	25	92	Route 2A / Route 140 south – Westminster	Eastern end of concurrency with Route 140
		92.568	148.974	26	93	Willard Road / Village Inn Road	Eastbound exit only
		93.479	150.440	27	94	Narrows Road / Depot Road
	Fitchburg	94.495	152.075	28	95	Route 31 – Fitchburg, Princeton
	Fitchburg–Leominster line	96.279	154.946	29		Mount Elam Road	Right-in/right-out connections only
		98.007	157.727	30	98	Merriam Avenue / South Street
	Leominster	99.269– 99.278	159.758– 159.772	31	99	Route 12 – Fitchburg, Leominster	Signed as exits 99A (south) and 99B (north) westbound
		100.355	161.506	32	100	Route 13 – Leominster, Lunenburg
		101.125	162.745	33	101	I-190 south / Mechanic Street – Worcester, Leominster	Northern terminus and exits 19A-B on I-190
	Lancaster	102.429	164.843	34	102	Mechanic Street / Harvard Street	Exit partially in Leominster
		103.497	166.562	35	103	Route 70 south (Lunenburg Road) – Lancaster, Lunenburg	Northern terminus of Route 70
		104.917	168.848	36	105	Shirley Road – Shirley
		106.419	171.265	37	106	Jackson Road – Devens, Reserve Forces Training Area	Signed as exits 106A (no public access) and 106B westbound; exit partially in Harvard
	Harvard	109.348– 109.357	175.979– 175.993	38	109	Route 110 / Route 111 – Harvard, Ayer	Signed as exits 109A (south/west) and 109B (north/east)
Middlesex	Littleton	113.050	181.936	39	112	Taylor Street – Littleton
		113.285– 113.317	182.315– 182.366	40	113	I-495 – Marlboro, Lowell	Signed as exits 113A (south) and 113B (north); exits 78A-B on I-495
	Boxborough	115.505	185.887	41	115	Newtown Road – West Acton, Littleton
	Acton	117.612	189.278	42	117	Route 27 – Maynard, Acton
		118.013	189.924	43	118	Route 111 north – West Acton	Westbound left exit and eastbound entrance; western terminus of concurrency with Route 111
	Concord	120.465	193.870	Eastern end of limited-access section
						Route 2A west / Route 119 west – Littleton Route 111 ends	Rotary; western end of concurrency with Route 2A; eastern terminus of Route 119; southern terminus of Route 111
				Western end of limited-access section
		121.691	195.843			Route 62 (Main Street) – West Concord, Maynard, Concord Ctr, Bedford	At-grade intersection
		123.901	199.399			Route 126 south (Walden Street) to Route 117 – Walden Pond, Waltham	At-grade intersection; northern terminus of Route 126
		124.824	200.885	50	125	Route 2A east – Concord, Lincoln	Eastern end of concurrency with Route 2A
	Lincoln	126.256	203.189	51		Bedford Road	At-grade intersection; to Route 2A
				Eastern end of limited-access section
	Lexington	128.527	206.844	Western end of freeway section
				52	127	I-95 / Route 128 – Attleboro, Peabody	Signed as exits 127A (south) and 127B (north)
		129.010	207.621	53	128	Spring Street – Lexington	No westbound exit
		130.002	209.218	54	129	Waltham Street – Lexington, Waltham	Westbound exit and eastbound entrance; signed as exits 129A (south) and 129B (north)
		130.894	210.653	55	130	Pleasant Street – Lexington	Eastbound exit and westbound entrance
		131.435	211.524	56	131	Winter Street – Belmont	No westbound exit
						Route 4 north / Route 225 west – Lexington, Bedford	No eastbound exit; southern terminus of Route 4; eastern terminus of Route 225
	Arlington–Belmont line	131.990	212.417	57	132	Dow Avenue – Arlington, Belmont
	Belmont	132.711	213.578	58	133	Park Avenue – Arlington
	Belmont–Arlington line	133.690	215.153	59	134	Route 60 – Belmont, Arlington
	Arlington–Belmont– Cambridge tripoint	134.130	215.861	60	135	Lake Street – East Arlington
	Cambridge	134.649	216.697			Alewife station	Eastbound exit only
		134.915	217.125	Eastern end of freeway section
		135.005	217.269			US 3 north / Route 16 east (Alewife Brook Parkway) – Medford, Woburn	Western end of concurrency with US 3 / Route 16
		136.354	219.440			Route 16 west (Huron Avenue) – Watertown, West Newton	Eastern end of concurrency with Route 16
		139.280	224.149			US 3 south (Memorial Drive)	Eastern end of concurrency with US 3
Charles River		139.349	224.260	Boston University Bridge
Suffolk	Boston	139.531	224.553			US 20 (Commonwealth Avenue) – Brighton, Kenmore Square
Norfolk	No major junctions
Suffolk	Boston	140.446	226.026			US 20 west (Commonwealth Avenue)	Kenmore Square; eastern terminus of US 20
		140.881	226.726			Route 2A west (Massachusetts Avenue)	Eastern terminus of Route 2A
		141.556	227.812			Route 28 south (Clarendon Street)	One-way southbound
		142.35	229.09			Beacon Street	Eastern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

• Freeway and expressway revolts

• Mass. Route 2 Current and Future Exit Numbers List