Four Corners Monument marks the unique point where Arizona, Colorado, New Mexico, and Utah meet, also touching the Navajo Nation and Ute Mountain Ute Tribe Reservation. The four-way junction emerged from territorial boundaries Congress created between 1850 and 1863 using lines of latitude and longitude, then surveyors fixed it on the ground over the following decades. Although those surveys contained errors, the courts later upheld the original markers as the legal borders. The site developed from a sandstone survey marker into today’s granite-and-metal monument and is now operated by Navajo Nation Parks and Recreation, drawing visitors to a rare political boundary made into a famous landmark.