SR 151 begins near the town center of Palmyra at US 2 (Main Street) at a stop-controlled intersection.

It first heads north-northwest along Warren Hill Road through a mostly rural area passing to the west of Whites Pond.

[1] After a short distance of houses lining the street, SR 43 and SR 151 briefly parallel the Sebasticook River before transitioning to a more rural setting zig-zagging west.

The road passes to the south of Great Moose Lake before crossing into the town of Athens briefly.

Eight miles (13 km) past Athens, the road reaches a small clearing which is the center of the town of Brighton.