The Mashantucket Pequot are a small Native American tribal nation of the Algonquian language community in the state of Connecticut. Within the tribe's Reservation, in 41°27′58″N 71°58′28″W / 41.46611°N 71.97444°W / 41.46611; -71.97444 Ledyard, New London County, Connecticut, the Mashantucket Pequot operate Foxwoods Resort Casino, the world's largest resort casino, in terms of gaming space and number of slot machines, and one of the most successful economically. The tribe achieved federal recognition by an act of Congress in 1983, the eighth tribal nation to have gained recognition through the political process. Membership is based on proven descent from tribal members listed in the 1900 Census.
The Mashantucket Pequot Indian Reservation is a land base held in trust by the Bureau of Indian Affairs (BIA) in Ledyard, Connecticut, in New London County, in the Norwich-New London metro area, and on the Pequot River, now known as the Thames River. The Tribe also has about 3.47 acres (14,000 m2) of off-reservation trust land in the town of Preston. The Pequot reservation was created by Connecticut Colony in 1666. Over time it had been reduced to less than an acre (4,000 m²), and the Pequot population reached a nadir of 20 or 30 in population in the early 20th century.
In 1976 the Mashantucket Pequot brought a successful lawsuit that contested the illegal appropriation of reservation lands by the state of Connecticut. They went on to expand their reservation by purchase. They placed repurchased lands into trust on behalf of the tribe with the BIA.