On the southern border between Arizona and Mexico is Organ Pipe Cactus National Monument, a Sonoran Desert wilderness area protecting the rare organ pipe cactus -- the park is the only place in the U.S. where this cactus grows. The park is much less developed than a typical national park, and all of the roads beyond the main highway are unpaved. Scenic drives and hiking are the best two ways to enjoy the park. Camping is available in the primitive Alamo Canyon Campground and at another developed campground near the visitor center.
Developed trails are in two main areas: the Puerto Blanco Mountains and the Ajo Mountains. The trails accessed from North and South Puerto Blanco Drives travel to historic mines such as Dripping Springs Mine, Victoria Mine, Baker Mine, and Milton Mine. The trail network is much longer in the Puerto Blanco Mountains. Along Ajo Mountain Drive are the Arch Canyon Trail and Estes Canyon-Bull Pasture Trails. These trails are especially scenic and the area contains the best clusters of organ pipe cacti in the park. Arch Canyon Trail leads to the top of a plateau with a natural rock arch. Estes Canyon-Bull Pasture Trail is a 4 mile loop that is a visitor favorite for its fantastic views.