"In the United States there are only two kinds of reserved lands that are well-known: military and Indian. An Indian Reservation is land reserved for a tribe when it relinquished its other land areas to the United States through treaties. More recently, Congressional acts, Executive Orders, and administrative acts have created Reservations. There are approximately 275 Indian land areas in the United States administered as Indian Reservations (reservations, pueblos, rancherias, communities, etc.). The largest is the Navajo Reservation of some 16 million acres of land in Arizona, New Mexico, and Utah. Many of the smaller Reservations are less than 1,000 acres with the smallest less than 100 acres. On each Reservation, the local governing authority is the tribal government. Military reservations are managed by the Department of Defense. Examples include army posts, marine bases, naval stations, and air force bases."
United States Geological Survey: http://www.usgs.gov/