Maine ( (listen)) is the easternmost state in the New England region of the Northeastern United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and northwest, respectively. The largest state by total area in New England, Maine is the 12th-smallest by area, the 9th-least populous, the 13th-least densely populated, and the most rural of the 50 U.S. states. It is also the northeasternmost among the contiguous United States, the northernmost state east of the Great Lakes, the only state whose name consists of a single syllable, and the only state to border exactly one other U.S. state. Approximately half the area of Maine lies on each side of the 45th parallel north in latitude. The most populous city in Maine is Portland, while its capital is Augusta.

Maine has traditionally been known for its jagged, rocky Atlantic Ocean and bayshore coastlines; smoothly contoured mountains; heavily forested interior; picturesque waterways; and its wild lowbush blueberries and seafood cuisine, especially lobster and clams. Coastal and Down East Maine have emerged as important centers for the creative economy, especially in the vicinity of Portland, which is also bringing gentrification.

The territory of Maine has been inhabited by aboriginal populations for thousands of years after the glaciers retreated during the last ice age. At the time of European arrival, several Algonquian-speaking nations governed the area and these nations are now known as the Wabanaki Confederacy. The first European settlement in the area was by the French in 1604 on Saint Croix Island, founded by Pierre Dugua, Sieur de Mons. The first English settlement was the short-lived Popham Colony, 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 and conflict with the local Indigenous people caused many to fail.

As Maine entered the 18th century, only a half dozen European settlements had survived. Loyalist and Patriot forces contended for Maine's territory during the American Revolution. During the War of 1812, the largely undefended eastern region of Maine was occupied by British forces with the goal of annexing it to Canada via the Colony of New Ireland, but returned to the United States following failed British offensives on the northern border, mid-Atlantic and south which produced a peace treaty that restored the pre-war boundaries. Maine was part of the Commonwealth of Massachusetts until 1820 when it voted to secede from Massachusetts to become a separate state. On March 15, 1820, under the Missouri Compromise, it was admitted to the Union as the 23rd state.