High Quality Content by WIKIPEDIA articles! The Four Corners Monument marks the quadripoint in the Southwestern United States where the states of Arizona, Colorado, New Mexico and Utah meet. It is the only point in the United States shared by four states, leading to this area being called the Four Corners region. The monument also marks the boundary between two semi-autonomous native American governments, the Navajo Nation, which maintains the monument as a tourist attraction, and the Ute Mountain Ute Tribe Reservation.