Interstate 91 (I-91) is an Interstate Highway in the New England region of the Northeastern United States. It provides the primary north–south thoroughfare in the western part of the region in the states of Connecticut, Massachusetts, and Vermont. 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 Quebec Autoroute 55. I-91 is the longest of the three Interstate highways whose entire route is located entirely within the New England states (the other two highways being I-89 and I-93) 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 New Haven, Connecticut; Hartford, Connecticut; Springfield, Massachusetts; Brattleboro, Vermont; White River Junction, Vermont; and St. Johnsbury, Vermont in order from south to north. I-91 runs closely parallel to U.S. Route 5 for its whole length.