The Phelps and Gorham Purchase was the forced sale, in 1788, of a portion of a large tract of land in western New York State owned by the Seneca nation of the Iroquois Confederacy to a syndicate of land developers led by Oliver Phelps and Nathaniel Gorham. The larger tract of land is generally known as the "Genesee tract" and roughly encompasses all that portion of New York State west of Seneca Lake, consisting of about 6,000,000 acres (24,000 km2).

Nathaniel Gorham was an American Founding Father, merchant, and politician from Massachusetts. He was a delegate from the Bay Colony to the Continental Congress and for six months served as the presiding officer of that body under the Articles of Confederation. He also attended the Constitutional Convention, served on its Committee of Detail, and signed the United States Constitution.