North Yarmouth, despite a similar name, shares no relation with adjacent Yarmouth. Many newcomers to the area figure that North Yarmouth is an area within Yarmouth, but the two are completely different towns. In fact, North Yarmouth is much more associated with Cumberland. The two towns share many departments, as well as organizations and SAD 51, the public school system. Yarmouth, however, operates its own school system. North Yarmouth, incorporated as a town in 1680, was actually the parent town to today's Yarmouth, which was incorporated in 1849 after separating from North Yarmouth.

 The town has a total area of 21.3 square miles (of which, 21.1 square miles of it is land and 0.2 square miles is water.

The area embracing North Yarmouth, first settled in 1636, was abandoned twice before successful final settlement in 1713. In 1646, William Royall purchased a farm on the river that, since, has borne his name. John Cousins, a few years previous, occupied a neck of land between branches of a stream and owned an island, both now bearing his name. These settlements were established in the vicinity, called by the Wabanakis, as ´Wescustogo¡. Yarmouth originally constituted the eastern portion of North Yarmouth; the ´North¡ in the name intended to differentiate it from Yarmouth, Massachusetts , on Cape Cod (Maine was then a part of Massachusetts). North Yarmouth was chartered on September 22, 1680, encompassing the area of the present Town of North Yarmouth and the towns of Harpswell (separating off in 1750), Freeport (separating off in 1789), Pownal (separating off from Freeport in 1808), Cumberland (separating off in 1821), and Yarmouth (separating off in 1849).