Route 140 is a 107.8-mile (173.5 km) long state highway which passes through parts of southeastern and central Massachusetts. The highway follows a southeast-northwest trajectory, running from U.S. Route 6 in New Bedford just north of Buzzards Bay northwest to an intersection with Route 12 in Winchendon, a few miles south of the border with New Hampshire.
The southern 19 miles (30 km) of Route 140 between New Bedford and Taunton is a freeway known as the Alfred M. Bessette Memorial Highway, or more commonly, the Taunton-New Bedford Expressway.
The section of modern Route 140 from West Boylston to Gardner was numbered Route 64 when it was first commissioned by 1933. By 1939, the entirety of the route was redesignated as Route 140, effectively extending existing Route 140 northwest, which had previously ended in Grafton.
In 1947, the Massachusetts Department of Public Works announced plans for a "Relocated Route 140", one of the first steps as part of its statewide expressway program. Between 1955-1970 the current route was widened and straightened, while the section south of Taunton, which runs to New Bedford, was built as an expressway. The New Bedford Expressway was to serve as a spur from the Fall River Expressway, connecting to points in the Boston metropolitan area. The creation of this spur was considered a key component of revitalizing the old port city of New Bedford.
Prior to the building of the freeway section, County Street (the section of road beginning at the Taunton River, and also known as County Road) brought the road southward through East Taunton, Berkley, Lakeville and East Freetown. The road, which runs parallel to the freeway and crosses it in Lakeville, merged with Route 18 in East Freetown, just north of the New Bedford city limits. The old alignment begins in front of the Silver City Galleria in Taunton.
Route 140 begins at an intersection with U.S. Route 6 (Kempton Street) and Brownell Avenue in Downtown New Bedford. This intersection is signed as exit 1 when traveling southbound on Route 140, but the exit number is nowhere to be found when traveling northbound. About a mile north, Route 140 comes to its first interchange, a cloverleaf with Interstate 195, which connects Providence to Cape Cod. Route 140 then curves slightly to the right to avoid New Bedford Regional Airport, which is accessible from Hathaway Road (exit 3). Route 140 eventually leaves New Bedford and enters East Freetown, providing an exit that drops off near the center of the village. Route 140 then runs parallel to Long Pond before curving slightly west. The freeway section of Route 140 ends a few miles north at exit 12, which is for Route 24. Meanwhile, Route 140 runs along County Street towards downtown Taunton.
Route 140 runs partially concurrent with Route 79 Truck in order to bypass certain sections of Route 79 proper. The two designations are concurrent from exit 10 (Route 79) to exit 12 (Route 24). At exit 12, Route 79 Truck leaves Route 140 for Route 24, where the truck route meets its parent at exit 9.
From the final interchange with Route 24 in Taunton, Route 140 extends northwest towards Taunton Center, having a brief conjuncture with US 44, just east of Taunton Center. As the two proceed to Taunton Green, a rotary begins with Route 140, US 44, and Route 138. Route 140 splits off from the rotary, bypassing Bristol County Courthouse. Route 140 brings its way through the northwest portion of Taunton, into Norton, past Wheaton College, and sharing a brief junction with MA-123. As Route 140 crosses the border from Norton to Mansfield, the Comcast Center is passed, followed by I-495. Route 140 shares a brief stretch of highway interchange with I-495, as the route then splits off and heads north through Mansfield Center and a junction with MA-106. Route 140 crosses into Foxboro, bearing an interchange with I-95, and further north a junction with US-1 North, with the US-1 South exit being another mile up the road in Wrentham. Route 140 loops through Wrentham Center, sharing a junction with Route 1A, and past King Philip Regional High School, into Franklin.
Route 140 enters Franklin from Wrentham, passing through Franklin Center, consisting of Dean College and Franklin/Dean College Station of the Franklin Commuter Rail line. Route 140 bypasses Franklin High School, and enters its second interchange with I-495 and also the second junction of the Franklin Commuter Rail line, at Forge Park/495 station, the final stop on the line. At this point, Route 140 extends west and heads into Bellingham. Route 140 spends a brief time in Bellingham, sharing a brief concurrence with Route 126, which extends north to I-495, and south into Woonsocket, Rhode Island. As Route 140 exits Bellingham, the road sharply turns north into the eastern edges of Mendon and Hopedale for a total of nearly three miles. Route 140 then enters Milford in a northwest trajectory, staying parallel to the Milford/Hopedale border for the routes duration in Milford. Route 140 enters a junction at Milford Regional Medical Center with Route 16, which leads westbound into Mendon and Hopedale Center, and eastbound to Route 85 and Route 109, both with terminations at Route 16, and interchanges with I-495. Route 140 enters a final small portion of Hopedale, then proceeds into the eastern part of Upton, passing through Upton Center and bypassing both Blackstone Valley Regional Technical High School and Nipmuc Regional High School.
Route 140 enters Grafton through the southeast, proceeding north and sharply turning west into Grafton Center and the town common. Route 140 bears right, northward, down a mile long hill that ends at a traffic light that begins a 1.5-mile concurrency with Route 122. Routes 140 and 122 proceed north through North Grafton, passing under the Mass Pike. Immediately after crossing under the Mass Pike, Route 122 splits off to west towards Millbury and Worcester, while Route 140 begins a concurrency with the western terminus of Route 30, and heads towards Shrewsbury. The concurrency with Route 30 is a quarter-mile long, as Route 30 splits east towards Grafton Station of the Framingham/Worcester Line MBTA Commuter Rail line, Tufts Animal Hospital, and the town of Westboro. As Route 140 enters Shrewsbury it briefly becomes an undivided, high-speed wide-median route, where it meets with U.S. 20 at an overpass. Two miles later, Route 140 meets Route 9 at an underpass. Route 9 West serves as the main road into Worcester from Shrewsbury and Northboro, while eastbound heads in the direction of Westboro and towards I-495. Route 140 extends north into Shrewsbury Center, and shares an interchange with Interstate 290 at the northern edge of town. Just north of the interchange, Route 140 enters Boylston, where it meets Route 70. After Route 70, the Wachusett Reservoir is seen, and Route 140 continues northwest into West Boylston, where in the center of town begins a brief concurrency with Route 12. The two extend north for one mile, as Route 12 splits north in the direction of Sterling and Clinton, following the western terminus of Route 110, and Route 140 extends northwest into the western portion of Sterling.
As Route 140 enters Sterling, there is an interchange with Interstate 190 which serves as the main source of transportation between Worcester to the south and Fitchburg to the north. Route 140 travels northwest to an intersection with Route 62 right before entering Princeton, home to Wachusett Mountain. Route 140 then joins a concurrency with Route 31 for a mile and a half, before crossing into Westminster and next to Wachusett Lake. Route 140 then meets Routes 2 and 2A at an overpass. Routes 2 and 2A run parallel with each other between Greenfield and Boston. Route 140 joins Route 2 Westbound for one exit, leaving the highway at Exit 24B. Route 140 shortly extends into Gardner. Route 140 meets with Route 101, before extending six and a half miles into Winchendon where Route 140 ends at an intersection with Route 12. Route 12 extends northwest towards Fitzwilliam and U.S. 202, which extends south to Templeton and north to Rindge, while Route 12 moves south to Ashburnham.
A section of Route 140 in Franklin was widened from two to four lanes wide. The $22 million project began in 2003 and was completed in 2007.
In Fall 2013, the ramp from Route 140 to I-495 south at exit 11 in Mansfield was completed. This ramp removed the need for traffic exiting the Xfinity Center in Mansfield to use a significant two-lane portion of Route 140.