Topsham is a town in Sagadahoc County, Maine, United States. The population was 9,100 at the 2000 census. It is part of the Portland–South Portland–Biddeford, Maine metropolitan statistical area. The town is home to the annual Topsham Fair.

Called Sawacook, the area was territory of the Pejepscot Abenaki Indians, a subtribe of the Anasagunticooks (now Androscoggins), who controlled the Androscoggin River. They lived and fished at Pejepscot Falls. But a plague, probably smallpox brought by Europeans, decimated the tribe's population in 1615-1616. On June 16, 1632, the area was granted by the Plymouth Council to Thomas Purchase and George Way, later acquired by Richard Wharton, and then in 1714 by the Pejepscot Company.

The first sawmill was built in 1716 on the Cathance River, and in 1717 the plantation received the name Topsham, named for Topsham in Devon, England. On January 31, 1764, it was incorporated as a town by the Massachusetts General Court.Shipbuilding and lumber mills were important early businesses, the latter especially active between 1750-1770. There was a gristmill and brickyard. Pejepscot Falls provided water power to operate mills, and industries would include a door, sash and stairway factory, shingle mill, watch factory, pottery maker, nail factory, pitchfork factory, two tanneries, tobacco manufacturer, two feldspar quarries and a marble works. In 1856, the Sagadahoc Agricultural & Horticultural Society erected its building and fairgrounds, and the town remains host to the annual Topsham Fair.

Maine (ⁱ/ˈmeɪn/) is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost portion of New England. It is known for its scenery—its jagged, mostly rocky coastline, its low, rolling mountains, its heavily forested interior and picturesque waterways—as well as for its seafood cuisine, especially lobsters and clams.

For thousands of years, indigenous peoples were the only inhabitants of the territory that is now Maine. At the time of European encounter, several Algonquian-speaking peoples inhabited the area. The first European settlement in Maine was by the French in 1604 on Saint Croix Island, by Pierre Dugua, Sieur de Mons. The first English settlement in Maine, the short-lived Popham Colony, was established by the Plymouth Company in 1607. A number of English settlements were established along the coast of Maine in the 1620s, although the rugged climate, deprivations, and conflict with the local peoples caused many to fail over the years. As Maine entered the 18th century, only a half dozen European settlements survived. Patriot and British forces contended for Maine's territory during the American Revolution and the War of 1812. Maine was part of the Commonwealth of Massachusetts until 1820, when it voted to secede from Massachusetts. On March 15, 1820, it was admitted to the Union as the 23rd state under the Missouri Compromise. Maine is the 39th most extensive and the 41st most populous of the 50 United States.