Maine also has several unique geographical features. Machias Seal Island, off its easternmost point, is claimed by both the U.S. and Canada and is one of five North American land areas whose sovereignty is still in dispute. Also in this easternmost area is the Old Sow, the largest tidal whirlpool in the Western Hemisphere.

Maine is the most sparsely populated state east of the Mississippi River. It is called the Pine Tree State; 90% of its land is forest.

The province within its current boundaries became part of Massachusetts Bay Colony in 1652. Maine was much fought over by the French and English during the 17th and early 18th centuries. After the defeat of the French in the 1740s, the territory from the Penobscot River east fell under the nominal authority of the Province of Nova Scotia, and together with present day New Brunswick formed the Nova Scotia county of Sunbury, with its court of general sessions at Campobello. American and British forces contended for Maine's territory during the American Revolution and the War of 1812. The treaty concluding revolution was ambiguous about Maine's boundary with British North America. The territory of Maine was confirmed as part of Massachusetts when the United States was formed, although the final border with British territory was not established until the Webster-Ashburton Treaty of 1842. (Indeed, in 1839 Governor Fairfield declared war on England over a boundary dispute between New Brunswick and northern Maine. Known as the Aroostook War, this is the only time a state has declared war on a foreign power. The dispute was settled, however, before any blood was shed.)

Because it was physically separated from the rest of Massachusetts and was growing in population at a rapid rate, Maine became the 23rd state on March 15, 1820 through the Missouri Compromise. This compromise allowed admitting both Maine and Missouri (in 1821) into the union while keeping a balance between slave and free states. Maine's original capital was Portland until 1832, when it was moved to Augusta.

The legislative branch is the Maine Legislature, a bicameral body composed of the Maine House of Representatives, with 151 members, and the Maine Senate, with 35 members. The Legislature is charged with introducing and passing laws.

The executive branch is responsible for the execution of the laws created by the Legislature and is headed by the Governor of Maine (currently John Baldacci, a Democrat). The Governor is elected every four years; no individual may serve more than two consecutive terms in this office. The current attorney general of Maine is G. Steven Rowe. As with other state legislatures, the Maine Legislature can by a two-thirds majority vote from both the House and Senate override a gubernatorial veto.

The judicial branch is responsible for interpreting state laws. The highest court of the state is the Maine Supreme Judicial Court. The lower courts are the District Court, Superior Court and Probate Court. All judges except for probate judges serve full-time; are nominated by the Governor and confirmed by the Legislature for terms of seven years. Probate judges serve part-time and are elected by the voters of each county for four-year terms.

Maine's agricultural outputs are seafood (notably lobsters), poultry and eggs, dairy products, cattle, wild blueberries, apples, and maple sugar. Aroostook County is known for its potato crops. Western Maine aquifers and springs are a major source of bottled water. Its industrial outputs consist of mainly paper, lumber and wood products, electronic equipment, leather products, food products, textiles, and bio-technology. Naval shipbuilding and construction remain key as well, with Bath Iron Works in Bath and Portsmouth Naval Yard in Kittery. Brunswick Naval Air Station is also in Maine, and serves as a large support base for the U.S. Navy. However, the BRAC campaign recommended Brunswick's closing, despite a recent government-funded effort to upgrade its facilities.

Maine ports play a key role in national transportation. Beginning around 1880, Portland's rail link and ice-free port made it Canada's principal winter port, until the aggressive development of Halifax, Nova Scotia, in the mid-1900s. In 2001, Maine's largest city of Portland surpassed Boston as New England's busiest port (by tonnage), due to its ability to handle large tankers. Maine's Portland International Jetport was recently expanded, providing the state with increased air traffic from carriers such as jetBlue.

Maine, where beaver trapping once created much wealth and many trading settlements, today has a small trapping industry that includes 3,157 resident, mostly part-time trappers. Still, the industry in Maine is larger than that of most Eastern states (Source: Portland Press Herald, January 23, 2005).

Maine has very few large companies that maintain headquarters in the state, and fewer than before due to consolidations and mergers, particularly in the pulp and paper industry. Some of the larger companies that do maintain headquarters in Maine include Fairchild Semiconductor in South Portland; IDEXX Laboratories, in Westbrook; UnumProvident, in Portland; L. L. Bean, in Freeport; Delorme, in Yarmouth; and MBNA, in Brunswick. Maine is also the home of The Jackson Laboratory, a non-profit institution and the world's largest mammalian genetic research facility.