Interstate 91

Interstate 91 Connecticut
Interstate 91 Massachusetts
Interstate 91 Vermont
I-91 Williams River Bridge - Rockingham, VT

As seen from parallel U.S. 5, this deck truss bridge carries Interstate 91 over the Williams River in the town of Rockingham, Vermont. 08/04/07

Overview

Interstate 91 provides a backbone route for western New England. Throughout Connecticut and a good portion of Massachusetts, I-91 serves populous areas and old industrial cities, including New Haven, Hartford and Springfield. North of there, it parallels the Connecticut River along the picturesque border of Vermont as it nears the “La Belle Province” of Québec.

High Priority Corridor

I-91 in Connecticut is part of High Priority Corridor 66: Interstate 91 Connecticut.

Parallel U.S. Routes

Interstate 91 primarily bypasses communities along U.S. 5 in Connecticut, Massachusetts and Vermont. I-91 also overlaps with U.S. 20 briefly through Springfield.

History

Within Massachusetts, Interstate 91 opened first from both Connecticut north to Springfield and from U.S. 5/Route 10 north of Greenfield to the Vermont state line in 1960. The 55 mile long route through the Bay State was completed in 1970.4

Interstate 91 from the Massachusetts State line north to Brattleboro in Vermont opened to traffic on November 1, 1958.1 This was the first route with controlled access completed in Vermont.

Within Vermont, Interstate 91 was built in stages in the late 1950s and through the 1960s. Specific opening dates for certain segments are as follows:2

  • Guilford to Vernon (5.879 miles) – November 1, 1958
  • Vernon to Brattleboro (1.942 miles) – July 31, 1959
  • Brattleboro (3.918 miles) – October 5, 1960
  • Brattleboro to Putney (11.055 miles) – December 6, 1961
  • Putney to Westminster (2.973 miles) – August 10, 1962
  • Derby (2.812 miles) – November 20, 1962
  • Derby (2.106 miles) – August 21, 1963
  • Westminster to Rockingham (9.437 miles) – November 7, 1963
  • Rockingham to Ascutney (16.319 miles) – 1965

Near St. Johnsbury (between Wells River and Glover), two alternative alignments for Interstate 91 were submitted by the state of Vermont to the federal Bureau of Public Roads. One route stayed close to U.S. 5 through McIndoe Falls, Barnet, St. Johnsbury and Lyndonville, then shifted to Vermont Route 122 through Wheelock and Sheffield to Glover. The other alignment took an entirely different course between Wells River and Glover, offering a more direct path through Danville. The first alternative was the one ultimately built.3

Though New Haven, Interstate 95 opened to traffic as part of the Connecticut Turnpike in 1958. The route was built on landfill through Long Wharf and across the Quinnipiac River. Route 34, the Oak Street Connector, tied into the turnpike by 1960. I-91 was added to the mix when it was completed in 1966.1 The complicated exchange joining the three limited access routes was dubbed the “Mixmaster Interchange.”

New Haven Harbor Crossing Corridor Improvement Program

Major reconstruction of the Mixmaster Interchange went to bid on April 28, 2010 as part of CTDOT’s $2 billion New Haven Harbor Crossing Corridor Improvement Program. Work involved relocating left exit ramps to Route 34 and I-91 from Interstate 95 north, eliminating a weaving traffic pattern, roadway widening and increasing the spacing between exits. Construction ran in tandem with the $433 million replacement of the Q Bridge (Pearl Harbor Memorial Bridge) along Interstate 95.5

The left side connection to Interstate 91 north from I-95 north was permanently replaced with a new right side exit on July 16, 2016. The change represented the last major traffic shift in the six-year project. Remaining work through September 2016 expanded each merge to two lanes and completed a fifth lane along I-95 north across the Pearl Harbor Memorial Bridge (scheduled for August 22). Final work on the overall interchange project wrapped up in 2017.6

Route Information

  • North End – Derby Line, VT

  • South End – New Haven, CT

  • Branch Routes – 4

  • Total Mileage – 290.37

Mileage

Connecticut – 58.00

  • Cities – New Haven, Meriden, Hartford
  • Junctions –

Massachusetts – 54.99

  • Cities – Springfield, Holyoke, Northampton, Greenfield

  • Junctions – Mass Pike

Vermont – 177.38

  • Cities – Brattleboro, St. Johnsbury, Newport
  • Junctions –

Source: December 31, 2021 Interstate Route Log and Finders List

I-91 Annual Average Daily Traffic (AADT)

Sources: MassDOT Transportation Data Management System 2018 AADT
2018 (Route Log) AADTs State Highways (VTrans)

Springfield, MA 1963
Springfield, Massachusetts – 1963.

Interstate 91 extended north 4.1 miles from the Connecticut state line to end at the South End Bridge in Springfield by 1960.4

Northeast Vermont 1978
Northeast Kingdom of Vermont – 1978 Vermont Official Highway Map.

The final stretch of Interstate 91 opened in the Green Mountain State was located near St. Johnsbury. I-93 was completed west to I-91 in 1982.

Costing $148 million, the I-91 Viaduct Rehabilitation Project replaced the decks of the elevated roadway taking I-91 through Springfield, Massachusetts. Work also made safety improvements at the exchange with Interstate 291. The bulk of construction was completed by January 2018, around nine months ahead of schedule. All northbound lanes for I-91 opened previously on December 8, 2017, followed by completion of the entrance ramp from State Street on December 18, 2017. Finished in Summer 2018, associated work to the south replaced the overpasses taking I-91 over Union and Broad Street.8

 Photo Guides

North End – Canadian International Border – Derby Line, Vermont

I-91 North

I-91 north at Derby Line, VT

Interstate 91 navigates through an S-curve northward into Derby Line, concluding in one mile at Caswell Avenue (Exit 29). 10/08/14

I-91 north at Derby Line, VT

Interstate 91 curves northeast away from parallel U.S. 5 (Main Street) to a folded diamond interchange (Exit 29) with Caswell Avenue along the Canadian border. 10/08/14

I-91 north at Derby Line, VT

The U.S. Customs Station lines the southbound roadway ahead of the Caswell Avenue overpass. Canadian Customs follows to the immediate north. 10/08/14

I-91 north at Derby Line, VT

Exit 29 departs from the north end of Interstate 91 to Caswell Avenue west to U.S. 5 (Main Street) in Derby Line. Quebec Autoroute 55 continues the freeway north 33 miles to Sherbrooke. Connections with Quebec Autoroute 10 lead travelers west to Montreal. 10/08/14

Caswell Ave at I-91

I-91 south at Derby Line, VT

Autoroute 55 transitions into Interstate 91 south leading into the community of Derby Line, Vermont. Exit 29 loops away from the freeway to Caswell Avenue beyond the U.S. border station. Photo by Shaun Ganley (03/22/15)

Caswell Ave east at I-91 - Derby Line, VT

Caswell Avenue parallels the international border east 0.4 miles from U.S. 5 (Main Street) to a folded diamond interchange with Interstate 91. 10/08/14

Caswell Ave west at I-91 - Derby Line, VT

Caswell Avenue west at the entrance ramp for Interstate 91 south to Newport, Lyndon and St. Johnsberry. 10/08/14

Caswell Ave at I-91 - Derby Line, VT

The southbound beginning of Interstate 91 from Caswell Avenue in Derby Line. 10/08/14

South End I-95 – New Haven, Connecticut

I-91 South at I-95

I-91 south at I-95 - New Haven, CT

Interstate 91 advances toward Downtown New Haven south from the end of U.S. 5 alongside State Street. 05/30/22

I-91 south at I-95 - New Haven, CT

A trumpet interchange connects Interstate 91 with Trumbull Street west to Yale University at Exit 3. 05/30/22

I-91 south at I-95 - New Haven, CT

Interstate 91 turns south through the Wooster Square neighborhood to the Mixmaster Interchange with I-95 (Connecticut Turnpike). Sign changes made in 2017 replaced Route 34 with MLK Boulevard for Exit 1. 05/30/22

I-91 south at I-95 - New Haven, CT

ConnDOT reconstructed a 7.2 mile long section of Interstate 95, including the exchange with I-91, in conjunction with the building of the Pearl Harbor Memorial Bridge over the Quinnipiac River. Work ran from 2010 to 2017. 05/30/22

I-91 south at I-95 - New Haven, CT

The ramp for Interstate 95 northbound across the Quinnipiac River into East Haven was expanded to two lanes during the New Haven Harbor Crossing Corridor Improvement Program. 05/30/22

I-91 south at I-95 - New Haven, CT

Interstate 95 travels east to New London and west to Bridgeport and Stamford along the Connecticut coastal region. Exit 1 to the Richard C. Lee Connector links I-91 with MLK, Jr. Boulevard on the south side of Downtown New Haven. 05/30/22

I-95 North at I-91

I-95 north at I-91 - New Haven, CT

The New Haven Harbor Crossing Corridor Improvement Program expanded I-95 east into the Mixmaster Interchange with I-91 with a fourth northbound lane. Route 34 was replaced with MLK Boulevard on signage for Exit 47 in 2017. 05/30/22

I-95 north at I-91 - New Haven, CT

The Pearl Harbor Memorial Bridge across the Quinnipiac River comes into view as Exit 46 departs from I-95 north for adjacent Long Warf Road to U.S. 1 (Water Street). 05/30/22

I-95 north at I-91 - New Haven, CT

Route 34 spurs west to Martin Luther King, Jr. Boulevard and Church Street in Downtown New Haven. A 24.37 mile long highway to Newtown, Route 34 was originally proposed to continue westward along a freeway to Derby Avenue and Route 122 (Forest Road) in West Haven. 05/30/22

I-95 north at I-91 - New Haven, CT

Route 34 stems west into Downtown New Haven from the Connecticut Turnpike while I-91 provides the main route to Hamden, Wallingford, Meriden and Hartford. 05/30/22

I-95 north at I-91 - New Haven, CT

Paralleling U.S. 5, Interstate 91 extends north from the Mixmaster Interchange with I-95 and Route 34 to the capital city of Hartford, Springfield, Massachusetts, and Brattleboro, Vermont. 05/30/22

I-95 South at I-91

I-95 south at I-91 - New Haven, CT

Advancing west to the Mixmaster Interchange with I-91 and Route 34, I-95 travels below grade west from East Haven through The Annex neighborhood in New Haven. 05/30/22

I-95 south at I-91 - New Haven, CT

Curving northwest to the Pearl Harbor Memorial Bridge, I-95 meets Interstate 91 north to Hartford and Route 34 west to Downtown New Haven in one mile. 05/30/22

I-95 south at I-91 - New Haven, CT

I-95 crosses the Quinnipiac River northwest from Stable Point into the systems interchange (Exits 48/47) with Interstate 91 and Route 34 (Oak Street Connector). 05/30/22

I-95 south at I-91 - New Haven, CT

An extradosed cable-stayed bridge, the Pearl Harbor Memorial Bridge accommodates ten overall lanes. 75 foot high towers support the 515 foot long center span and 249 foot long side spans.<sup>7</sup> 05/30/22

I-95 south at I-91 - New Haven, CT

Traffic partitions with three lanes continuing along I-95 south toward Bridgeport, a single lane for the Oak Street Connector to Downtown New Haven and two lanes for Interstate 91 north to Wallingford and Meriden. 05/30/22

I-95 south at I-91 - New Haven, CT

Route 34 branches west from Exit 47 to Martin Luther King, Jr. Boulevard along the south side of Downtown New Haven. Exit 48 connects with Exit 2 from I-91 north to Hamilton Street. 05/30/22

Oak Street Connector – East at I-91 I-95

Route 34 east at I-91/95 - New Haven, CT

S Frontage Road (Route 34) transitions east onto the Oak Street Connector leading into the Mixmaster Interchange with I-91/95 beyond Orange Street. 03/28/23

Route 34 east at I-91/95 - New Haven, CT

The Oak Street Connector is a short freeway spur linking Downtown New Haven with both Interstate 95 and I-91 north to Hartford. 03/28/23

Route 34 east at I-91/95 - New Haven, CT

Traffic partitions from the Oak Street Connector (Route 34) with two lanes joining I-95 across the Q Bridge to East Haven and I-91 to North Haven. 03/28/23

I-91 North

I-91 north after I-95 - New Haven, CT

The first confirming marker for Interstate 91 precedes Exit 3 to Trumbull Street in New Haven. Exit 2 is accessible only from the ramp to I-91 from I-95 southbound. 05/30/22

I-91 South End Throwback

I-91 South at I-95

I-91 south at I-95 - 2005

Ramps for Hamilton Street (Exit 2) and Route 34 (Richard C. Lee Connector) depart in advance of the Mixmaster Interchange with I-95. 06/26/05

I-91 south at I-95 - 2005

Route 34 spurs west from Exit 1 into Downtown New Haven. 06/26/05

I-95 North at I-91

I-95 north at I-91 - 2007

A large diagrammatic overhead preceded the exchange (Exits 47/48) with Route 34 west and I-91 north at the Howard Avenue overpass along Interstate 95 north. 07/27/07

I-95 north at I-91 - 2007

A left exit ramp formerly joined Interstate 91 northbound in 0.75 miles. It was replaced by a new flyover departing from the outside lanes. 07/27/07

I-95 north at I-91 - 2007

Exit 47 to Route 34 (Richard C. Lee Connector) was also relocated from the left side of I-95 north to a new flyover separating from the right lane. 07/27/07

I-95 north at I-91 - 2007

Traffic formerly separated with two lanes for I-91 and I-95 at Left Exit 48. 07/27/07

Sources:

  1. Celebrating the 50th Anniversary of the Eisenhower Interstate Highway System: Previous Interstate Facts of the Day by the Federal Highway Administration (FHWA).
  2. Outline History of Vermont State Highways – National Highway Week, September 19-25, 1965. Prepared for informational purposes only by the Vermont Department of Highways.
  3. Vermont’s 14-Year Planning Program on the Federal Aid Highway System by the Vermont Department of Highways (April 1963).
  4. Interstate 91 Massaschusetts. BostonRoads.com.
  5. “Next up: Reconstructing the Route 34, I-91 interchange (video, animation).” New Haven Register, April 25, 2010.
  6. “New Haven Interstate 95-91 interchange to head in new direction for first time in 60 years.” New Haven Register, July 10, 2016.
  7. Pearl Harbor Memorial Bridge, Connecticut, US. Road Traffic Technology, web site.
  8. “I-91 Springfield viaduct project ahead of schedule.” Greenfield Recorder (MA), January 2, 2018.

Page updated March 31, 2023.