Organ Pipe Cactus National Monument
may be reached either by AZ 85 from Gila Bend (75 miles to the visitor center), or by AZ 84 from Tucson (140 miles). The nearest towns are both very small - Lukeville on the south side, by the Mexican border, and Why to the north.
PDF format map of Organ Pipe Cactus National Monument
, from the National Park Service (252 kb).