Organ Pipe Cactus National Monument: Ajo Mountain Drive

Arguably the best way to get a representative view of Organ Pipe Cactus National Monument, the Ajo Mountain Drive is a 21-mile scenic drive into, you guessed it, the Ajo Mountains, located within the park’s boundaries. Sometimes called the Ajo Mountain Loop Road, this drive takes visitors on a journey through rugged mountains while offering breathtaking views of the surrounding desert. And, yes, on this drive you’ll see plenty of Organ Pipe cacti!

Organ Pipe Cactus National Monument covers 516 square miles of Southern Arizona, so you could spend a month there and not see all of this isolated, biodiverse jewel of the National Park System (NPS). But most people spend significantly less than a month there—and Ajo Mountain Drive is for them.

Careful drivers can navigate this 21-mile loop in most vehicles and it traverses much of what makes Organ Pipe great including unique desert flora, steep mountains, and dramatic views.

Ajo Mountain Drive © Rex Vogel, all rights reserved

It’s no surprise that the Ajo Mountain Drive is the most popular scenic drive in the monument. It takes you through an excellent overview of the monument’s landscape bringing visitors through desert washes and up into the Ajo Mountains. For those wanting some good views and photographs of cacti, the drive provides ample opportunities to see large stands of its namesake cacti, the organ pipe cacti, as well as saguaros, cholla, and barrel cacti.

The Ajo Mountain Drive is a 21-mile graded, one-way dirt road. The drive takes approximately 2 hours and has been designed so that a passenger car driven with caution may be taken over it safely. Trailers, buses, and motorhomes over 25 feet are prohibited on the drive. After the first mile, the drive becomes a one-way road, so be prepared to finish the entire 21-mile loop.

Ajo Mountain Drive © Rex Vogel, all rights reserved

Before you embark, stop at the monument’s visitor’s center to pay your entrance fee and pick up a guide to the route; numbered stakes along the road correspond to entries in the guide.

You can also follow along with the audio tour/written guide on the NPS App or download a PDF version of the guide.

There are four picnic sites provided on the drive. Stops #6 has a shaded picnic area and Estes Canyon after stop #11 has a ramada and backcountry restrooms. The Ajo Mountain Drive also provides access to the trailheads for the Arch Canyon, Old Pima County Road, and Estes Canyon/Bull Pasture trails. 

By the way, I have a series of posts on Organ Pipe Cactus National Monument:

Ajo Mountain Drive © Rex Vogel, all rights reserved

Leaving the visitor’s center, head east on Ajo Mountain Drive which is across State Route 85 from the visitors center.

In the early going, you’ll see plenty of Sonoran Desert staples such as saguaros, chollas, and ocotillos along this wide, washboarded dirt road. Straight ahead, to the east, are the craggy peaks of the Ajo Range which is topped by 4,819-foot Mount Ajo. You’ll get a closer look at the mountains later but for now enjoy the view along the road—which splits and becomes a narrower, one-way route at Mile 2.

Two miles past the split, you’ll spot your first organ pipe cactus (Stenocereus thurberi), and a mile later these aptly named, many-limbed columnar cactuses line both sides of the road. The monument harbors most of the U.S. population of this species—which, like the saguaro, tends to grow on south-facing slopes. While there are 30 other cactus species at the monument, the organ pipes are among the most visible and dramatic and you can enjoy them over lunch at the shaded Diablo Canyon Picnic Area, just ahead.

Ajo Mountain Drive © Rex Vogel, all rights reserved

Past the picnic area, a paved section of road, one of several on this drive, winds into the foothills of the Ajo Range offering lovely panoramas around every corner. Healthy organ pipes proliferate on seemingly every hillside—on average, these cactuses’ stems grow about 2.5 inches per year.

Also, watch for a natural arch high above the road; from the Arch Canyon Trailhead, at Mile 9, you can hike a short, easy trail that offers good views of the rock formation. (An unmaintained and much steeper extension of that trail will take you up to the arch, but it isn’t for the faint of heart.)

The road then curves to the south and around the mountains providing nice views of the cliffs on the left. Past the Estes Canyon-Bull Pasture Trailhead which leads to another lovely hike, you’ll pass through a forest of healthy organ pipes and tall saguaros.

Ajo Mountain Drive © Rex Vogel, all rights reserved

Around Mile 13, the organ pipes fade away as the road rolls into a flatter area that isn’t as ideal for those cactuses and numerous chollas, ocotillos, and prickly pears take their place. But the monument’s crown jewels return a few miles later offering one more look at a plant you aren’t likely to see elsewhere.

Eighteen miles in, you’ll return to the two-way road you took at the start of the drive. Turn left and retrace your route for 2 miles back to SR 85 where you can think about which of Organ Pipe’s 516 square miles you’ll explore the next time you visit.

Some reminders

Water is not available anywhere along the drive so carry plenty with you. Fires and camping are not allowed on the drive. Pets are not allowed on trails or in the backcountry. They must be leashed at all times. Please do leave pets unattended.

Do not cross washes when flooded. Do not pick up hitchhikers. Report any suspicious activity to park staff immediately. Do not contact any suspicious persons. If you see them in distress, contact a ranger for help. Remember that you’re only a few miles from Mexico.

Ajo Mountain Drive © Rex Vogel, all rights reserved

Tour guide

  • Length: 21-mile loop
  • Directions: From Ajo, go south on State Route 85 for 33 miles to Ajo Mountain Drive. Turn left (east) onto Ajo Mountain Drive and continue 21 miles around the loop and back to SR 85.
  • Vehicle requirements: A high-clearance, four-wheel-drive vehicle such as an SUV or truck is recommended, but the route is passable in a standard sedan in good weather.
  • Special consideration: NPS fees apply. Additionally, while the monument is safe to visit, crossings and other illegal activities do occur along the U.S.-Mexico border. Stay on maintained park roads, do not pick up hitchhikers, and report any suspicious behavior or distressed people you encounter to the monument’s staff or the Border Patrol.
  • Warning: Back-road travel can be hazardous so be aware of weather and road conditions. Carry plenty of water. Don’t travel alone and let someone know where you are going and when you plan to return.

Worth Pondering…

Alone in the open desert, I have made up songs of wild, poignant rejoicing and transcendent melancholy. The world has seemed more beautiful to me than ever before.

I have loved the red rocks, the twisted trees, and sand blowing in the wind, the slow, sunny clouds crossing the sky, the shafts of moonlight on my bed at night. I have seemed to be at one with the world.

—Everett Ruess