Four Corners States

Arizona, Colorado, New Mexico, and Utah meet at Four Corners — the only quadripoint in the United States. A quadripoint is a point at which four distinct territories share a single border. The Four Corners intersection is the result of the rectangular land survey system used to establish western U.S. state borders in the 19th century: the borders of all four states are defined by lines of latitude and longitude, and they converge at a single legal point.

All four states were established from territory acquired in the Mexican Cession of 1848, following the Mexican-American War. Colorado achieved statehood first in 1876; Utah followed in 1896; and New Mexico and Arizona were admitted together in 1912, the last two of the contiguous 48 states. The four-state boundary at their corners was established by the surveys of 1868 and 1875 and confirmed by Congress.

The Four Corners Monument is located at approximately 36.9991°N, 109.0453°W, on land administered by the Navajo Nation. The current structure, built in 1992, consists of a circular concrete plaza with a central brass disk engraved 'Four Corners USA' and the seals of all four states and the two tribes — the Navajo Nation and the Ute Mountain Ute Tribe — whose reservations meet at the same point. An entry fee is required; the monument is operated by Navajo Parks and Recreation.

A 2009 resurvey by the National Geodetic Survey found that the monument stands approximately 1,807 feet east of the point that a GPS-based calculation would identify as the precise intersection of the original survey lines. The legal boundary, however, has been confirmed by Congress at the monument's existing location, following the rule that a boundary established by survey and accepted by adjacent states cannot be moved simply because a later survey finds an error. The legal Four Corners remains where the monument stands.

Four Corners is also the name of a census-designated place in Natrona County, Wyoming, located near Casper with a population of approximately 3,200. It has no connection to the famous quadripoint. The name follows a common western U.S. naming pattern — 'four corners' refers to the corners of adjacent square sections of land in the Public Land Survey System, a name that appears dozens of times across the country for unincorporated communities.

Searches for 'Four Corners Wyoming' sometimes appear alongside results for the AZ/CO/NM/UT monument. The two have no geographic or historical relationship. The famous Four Corners is always the quadripoint in the southwestern United States where Arizona, Colorado, New Mexico, and Utah meet.