It is a unique geographic location at the junction of four US States: * the Soutwest corner of Colorado. * the Northwest corner of New Mexico, * the Northeast corner of Arizona and * the Southeast corner of Utah.
The Four Corners is the point where the southwest corner of Colorado, the northwest corner of New Mexico, the northeast corner of Arizona and the southeast corner of Utah occupy exactly the same point on the earth's surface.
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's being called the Four Corners region.