The Passumpsic River () is a tributary of the Connecticut River, in Vermont. Though primarily a Caledonia County river, it is the only river to flow through all three counties of the Northeast Kingdom. Course The river arises in two branches: east and west. The East Branch begins just north of East Haven. It flows southwest through Hartwellville in East Haven, then into East Burke. The West Branch starts as several small forks near Crystal Lake, northeast of Sutton. The Montreal, Maine and Atlantic Railway lines follows the West Branch of the Passumpsic until it converges with the East Branch in Lyndonville. From Lyndonville, the river proceeds southerly through St. Johnsbury Center, St. Johnsbury, Passumpsic, and Barnet, and into the Connecticut River near Nine Island. East Branch The East Branch originates about 1/2 mile southeast of Sukes Pond, Brighton, in Essex County. Route 114 nearly parallels it as it runs south-southeast. It soon enters Caledonia County. It is joined by Jack Brook near Howard Brook Road in Newark. It then turns south southwest. Just before entering East Haven, it is joined by Mill Brook/King Brook entering from the east. It is then joined by the confluence of Bean Brook and Whetstone Brook just inside the town of East Haven, back in Essex County. It goes through Hartwellville, in the town of East Haven, then crosses into Caledonia County for good. In Burke, a mile downstream, it is joined on the south by Flower Brook which flows mainly from the east. Duck Pond drains into it. It is followed by Route 5A and flows through East Burke. It converges with the west branch before 5A joins US Route 5. West Branch The West Branch first exits out the west side of Newark Pond in Newark. It flows briefly through Barton, back into Newark, then into Burke. Burke Mountain The northeast and northwest sides of Burke Mountain drain into Dish Mill Brook, thence into the East Branch of the Passumpsic River. The southwest end of Burke Mountain drains into Mountain Brook, thence into the East Branch of the Passumpsic River. The south slopes and southeast side of Burke Mountain drain into Weir Mill Brook, thence into Bog Brook, the Moose River, and the Passumpsic River. Burke It proceeds south-southwest. Arcadia Brook flows into it from the north near Arcadia Lane. West Brook flows into it from the northwest near VT 5A, which