 Williamstown was laid out as a township in 1739 and incorporated in 1765.Its early development was centered in the modern town center to the north, and the southern part of the town was not laid out until 1765.South Williamstown, now Five Corners, was formed out of the junction of four large parcels of land, and developed in the late 18th century as a stop on the main north-south stagecoach route (today United States Route 7).