Dayton is a town in York County, Maine, United States; the town is located near the Saco-Biddeford city area. Dayton borders Biddeford by land, and borders Saco on the Saco River. It is also part of the Portland–South Portland–Biddeford, Maine metropolitan statistical area. The population was 2,129 at the 2020 census. Dayton is one of the smallest towns in York County.
The area was once inhabited by the Sokokis (or Saco) Indians, who hunted and fished along the Saco River. The old Sokokis Trail is now Route 5, which passes through Dayton. In 1664, Major William Phillips purchased from the sagamore the land which would become Little Falls Plantation—today the towns of Hollis, Dayton and part of Limington. In 1728, a stockaded fort which contained a trading post was built a half mile below Union Falls. Called the Saco Truck House or Saco Block House, the garrison was maintained throughout the French and Indian War until the fall of Quebec in 1759.