Page Type Page Type: Mountain/Rock
Location Lat/Lon: 32.03000°N / 112.69°W
Additional Information Elevation: 4808 ft / 1465 m
Sign the Climber's Log


Mount Ajo is the tallest mountain in Organ Pipe Cactus National Monument. It is located in a spectacular desert setting, and climbing it is a great way to experience the Sonoran Desert. Located in the Ajo Range, Mt. Ajo is a beautiful mountain, with vibrant red, yellow and brown volcanic rock; steep canyons; and lush desert vegetation. The eastern half of Mt. Ajo forms part of the western boundary of the Tohono O’odham Indian Reservation. Mt. Ajo is most frequently climbed via an unmaintained class 1 trail. From the summit there is a vast view of the eastern portion of Organ Pipe Cactus National Monument, the Tohono O’odham Reservation, and surrounding ranges in Arizona and Mexico.

The origin of the name “Ajo” is unclear. In Spanish, “ajo” means “garlic.” Another explanation is that the Tohono O’odham people used a pigment called “au’auho” for face painting, and that the Spanish modified the word to “Ajo.”

Organ Pipe Cactus National Monument
Organ Pipe Cactus National Monument was established to protect the organ pipe cactus, which is primarily a tropical species. Although common in Mexico, the organ pipe cactus does not tolerate frequent frosts, so it reaches its northern range limit in and around the monument. In the monument, it occupies primarily warmer, south-facing slopes. The 330,000-acre monument, together with the adjacent 860,000-acre Cabeza Prieta National Wildlife Refuge to the west and nearby Pinacate Biosphere Reserve in Mexico, comprise a large protected area.

Mt. Ajo is located in the Arizona Upland subdivision of the Sonoran Desert, which is a relatively wet part of the Sonoran Desert. Organ Pipe Cactus National Monument receives over eight inches of rain per year, mostly during the winter and summer. This area contains 26 species of cacti, notably the organ pipe, the south-leaning fishhook barrel, and saguaro (pronounced “suh-wah-roe”) cacti, and several species of cholla (including teddy bear, pencil, staghorn, buckhorn, and hanging fruit), hedgehog, pincushion, and prickly pear cacti. Foothill paloverde trees, mesquite, ocotillo, jojoba, several agave species, and other desert plants are also quite common. Near the top of Mt. Ajo are small stands of oaks and junipers, relics of a cooler, wetter time when such species were more widespread. There are also several desert animal species, including the pig-like javelina, bighorn sheep, coyotes, snakes (including several venomous species), lizards, cactus wrens, canyon wrens, gila woodpeckers, phainopeplas, and northern mockingbirds.

See "A Natural History of the Sonoran Desert" published by the Arizona Sonora Desert Museum, for further information on the ecology of the Sonoran Desert.

Getting There

From appropriately named Why, Arizona, drive 22 miles south along Highway 85 until reaching the Organ Pipe Cactus National Monument visitor center on the right (west). You should stop at the visitor center to inquire about a pass to drive on Ajo Mountain Drive. Directly east from the visitor center across Highway 85 is Ajo Mountain Drive. Drive up Ajo Mountain Drive, taking the left side of the loop when it becomes one-way. The distance from the beginning of the road to the Estes Canyon/Bull Pasture Trailhead is 11 miles.

Red Tape

There is a $5 fee for driving the monuments backroads, including Ajo Mountain Drive. This fee covers driving in the park for 7 days. There is also a $3 per person fee for visiting. However, visitors may instead purchase a National Parks Pass, which costs $50 and allows unlimited visitations to all national parks for a year, or purchase an Organ Pipe Cactus National Monument annual pass for $15. Online information on Organ Pipe Cactus National Monument is available, or call the monument at (520) 387-6849.

Border Issues

Organ Pipe Cactus National Monument is located along the Arizona-Mexico border. Unfortunately, many associated border problems have spilled over into the monument. Car thefts and drug smugglers are occasionally reported in the monument near the border. In August 2002, a park ranger was killed along Puerto Blanco Road by a suspected drug smuggler. The U.S. Border Patrol frequently patrols the monument's backroads.

It is possible to enter Mexico from the monument through the border crossing at Lukeville, Arizona. A market is located in Lukeville where food can be purchased. The town of Sonoyta, Mexico, is two miles from the border.

When To Climb

October-May. Summers are blisteringly hot, with temperatures frequently exceeding 100 degrees Fahrenheit. There are gorgeous wildflower displays during the spring. Carry plenty of water—there are no reliable water sources. However, be aware of weather forecasts when planning to visit. It can also be quite cold in the desert and at nearly 5000' Ajo can get far colder than you might expect. Cold fronts reach as far south as Organ Pipe and November through March can have near freezing nights in the campgrounds. If not windy, the days can moderate.


No camping is allowed along the route. There are two campgrounds in the monument: Twin Peaks Campground, which has 208 units and is located near the visitor center ($10/night), and Alamo Campground, which has four units and is more rustic, lacking running water ($6/night). Camping information is available online. Nearby Ajo has a few modest hotels, which aren’t great, but are clean.

Mountain Conditions

Weather conditions are available online. Online information on Organ Pipe Cactus National Monument is also available, or call the monument at (520) 387-6849.



Children refers to the set of objects that logically fall under a given object. For example, the Aconcagua mountain page is a child of the 'Aconcagua Group' and the 'Seven Summits.' The Aconcagua mountain itself has many routes, photos, and trip reports as children.