The 496,330-acre (200,860 ha) monument is located in the Mesilla Valley in southern New Mexico, surrounding the city of Las Cruces in Doña Ana County.

[6] The Aden Lava Flow Wilderness is here[2] and there are 243 known archaeological sites within the monument,[4] including some of the earliest Native American settlements and petroglyphs known from three different tribes.

[2] More recently the land was used by William H. Bonney, better known as the outlaw Billy the Kid, and Geronimo, a leader during the Apache Wars, both of whom lived in various parts of New Mexico in the 19th century.

[7] The monument includes sites where World War II bombers practiced their targeting, as well as Kilbourne Hole in the Potrillo volcanic field, where American astronauts trained for lunar missions in the 1960s.

A poll found that 60 percent of the local voters favored establishing this land as a 500,000-acre national monument.