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