Organ Pipe Cactus National Monument (Ariz.)

Organ Pipe Cactus National Monument is a U.S. national monument and UNESCO biosphere reserve located in southern Arizona that shares a border with the Mexican state of Sonora. The park is one of the few places in the United States where the senita and organ pipe cactus grow wild. Along with these species, many other types of cacti and other flora native to the Yuma Desert section of the Sonoran Desert region grow in the park. Organ Pipe Cactus National Monument is 517 sq mi (1,340 km2) in size. In 1976 the monument was declared a Biosphere Reserve by UNESCO, and in 1977 95% of the monument was declared a wilderness area. In 1937 the land was officially opened as a national monument. At the north entrance of the park is the unincorporated community of Why, Arizona; the town of Lukeville, Arizona at the park's southern border is a border crossing point to Sonoyta, Sonora, Mexico. Organ Pipe Cactus National Monument is bordered to the northwest by Cabeza Prieta National Wildlife Refuge and to the east by the Tohono Oʼodham Indian Reservation.