For thousands of years inhabited by indigenous peoples, including the two historic Native American tribes (the Algonquian-speaking Abenaki and the Mohawk), much of the territory that is now Vermont was claimed by the French colony of New France. France ceded the territory to Great Britain after being defeated in 1763 in the Seven Years' War. For many years, the nearby colonies, especially the provinces of New Hampshire and New York, disputed control of the area (then called the New Hampshire Grants). Settlers who held land titles granted by New York were opposed by the Green Mountain Boys militia, which supported the claims of the many settlers whose claims were based on grants from New Hampshire.

Ultimately, those settlers prevailed in creating an independent state, the Vermont Republic. Founded in 1777 during the Revolutionary War, the republic lasted for fourteen years. Aside from the Thirteen Colonies, Vermont is one of only four U.S. states that were previously sovereign states (along with California, Hawaii, and Texas). In 1791 Vermont joined the U.S. as the 14th state—the first to be admitted to the union after the original 13 colonies. While still an independent republic, Vermont was the first of the future United States to abolish adult slavery. It played an important geographic role in the Underground Railroad, helping refugee American slaves escape to freedom in Canada.