[2] Route 12 begins at the New Hampshire state line on the Connecticut River in the town of Weathersfield.

It continues north along the west bank of the Connecticut River, overlapped with U.S. Route 5, until Hartland.

It then heads northwest to Woodstock and then north through Montpelier to end at Vermont Route 15A in Morrisville.

Vermont Route 12 runs parallel to Interstate 89 from the Woodstock/Hartford vicinity to Montpelier.

It provides an alternate route to VT 12 between Randolph and Northfield, via Braintree, Granville and Roxbury.