Interstate 91 (
I-91) is an
Interstate Highway in the
New England region of the
United States. It provides the primary north–south thoroughfare in the western part of New England. The Interstate's southern end is in
New Haven, Connecticut at
Interstate 95 and its northern end is at
Derby Line, Vermont, a village in the town of
Derby, at the
Canadian border, where it continues past the
Derby Line-Rock Island Border Crossing as
Autoroute 55. I-91 is the longest of three Interstate highways whose entire route is located within the New England states, and is also the only primary (two-digit) Interstate Highway in New England to intersect all five of the others that run through the region. The largest cities along its route are
Springfield, Massachusetts,
Hartford, Connecticut, and
New Haven, Connecticut, in order from north to south.