Organ Pipe Cactus National Monument protects a vast stretch of southern Arizona desert along the Sonora, Mexico, border, preserving part of the Yuma Desert within the Sonoran Desert. One of the few U.S. places where both organ pipe cactus and senita grow naturally, it is also a UNESCO biosphere reserve. Established in 1937 and later largely designated wilderness, it adjoins other protected and Indigenous lands. Its border location has also brought violence, trafficking closures, and controversy over wall construction, especially where archaeological sites and places sacred to the Tohono Oʼodham Nation make the area important not only ecologically but culturally and politically as well.