Four Corners Monument
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 the area being named 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.
Four corners (Canada)
The establishment of Nunavut in 1999 led to the creation of Canada's only quadripoint at this location. In the legal definition of Nunavut, its border is specified as "Commencing at the intersection of 60°00'N latitude with 102°00'W longitude, being the intersection of the Manitoba, Northwest Territories and Saskatchewan borders". Since the intersection does not lie exactly at those coordinates, the laws are not perfectly clear about whether or not the Nunavut–NWT boundary, which has not been completely surveyed, is to meet the others in a quadripoint. Surveys began in 2011.