 SR 4 begins at the New Hampshire state line, where the roadway continues south as NH 4 towards Dover.From South Berwick, SR 4 runs in a northeasterly direction through the town of North Berwick, bypassing the center of Sanford to the east, and intersects US 202 in Alfred.SR 4 runs concurrently with US 202 for to the city of Auburn via the towns of Gorham, Windham and Gray.