At its eastern end, NH 26 meets Maine State Route 26 which connects with the city of Portland in the south.

The highway begins in the west at the state line between Lemington, Vermont and Colebrook, New Hampshire along the Connecticut River.

From Colebrook to Dixville, NH 26 runs tightly along the Mohawk River, a tributary of the Connecticut.

The site of the 15,000-acre (61 km2) Balsams Grand Resort Hotel, which opened during the Civil War but was closed in 2011, is also located along NH 26.

NH 26, heading southeast, crosses the Androscoggin River and then runs along the southwestern side of Umbagog Lake.

It is only 0.013 mi (68.64 ft) long, but is signed and recognized by VTrans as a state route.