High Quality Content by WIKIPEDIA articles! Interstate 91 (abbreviated 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; its northern end is at Derby Line, Vermont, a village in the town of Derby, at the Canadian border, where it continues 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.