While we were boondocking south of Ajo, AZ, we did a day trip to Organ Pipe Cactus National Monument. The rangers suggested the Bull Pasture Hike as one of the best in the Monument so off we went out Ajo Mountain Road to the trailhead.
Ajo Mountain Drive is the main backcountry scenic route in Organ Pipe Cactus National Monument. Obtain your day pass from the Visitor Center located on the west side of Hwy 85 about 5 miles from the Mexican Border. It is mostly unpaved and heads towards the foothills of the Ajo Range, the high, rocky ridge that forms the eastern boundary of the Monument.
Ajo Mountain Drive is only 21 miles in length, but the drive takes around 90 minutes (without stops) since the road is often narrow and very bumpy. The drive starts along AZ 85 opposite the visitor center and is two-way for a few miles then narrows and changes to one-way (clockwise) at the start of the loop section.
The scenery is magnificent, cactus plains separated by imposing volcanic mountains that are covered with a plethora of desert plants.
At marker #15, 11.1 miles from the highway, is Estes Canyon/Bull Pasture Trailhead. The Bull Pasture and Estes Canyon trails, as well as the trail ascending Mount Ajo Peak all share this common trail head. The Bull Pasture/Estes Canyon loop is perhaps the best hike in the national monument. It is a 3.5-mile loop to Estes Canyon and Bull Pasture which is an elevated plateau where ranchers grazed cattle in the past.
The trail starts at the Estes Canyon Picnic Area. There are restrooms here. The trailheads are on the East side of the road. Estes Canyon trail is to the left and Bull Pasture trail is straight ahead. Estes Canyon trail starts off with a gentle grade and ends with a steep ascent to join Bull Pasture trail ½ mile from the trail end.
Trailhead to Bull Pasture is 2 miles for Estes Canyon trail and 1½ miles for Bull Pasture trail. The altitude change is 950 feet.
At Bull Pasture Overlook you can look down on the elevated grasslands that comprise Bull Pasture – an important summer pasture from the areas’ ranching past. From this vantage, you can see Sonoyta Valley directly to the south and beyond that is Mexico.
With panoramic views of the lower Sonoran Desert, tons of wildflowers in spring, and lots of organ pipe cactus, this is a trail that can do no wrong.
We started back down the trail and took the Estes Canyon arm of the loop in the late afternoon. The light on the Ajo Mountains was magnificent.
How to get to Ajo Mountain Drive
From I-8 at Gila Bend, take Exit 115 to AZ 85 south 58 miles to The entrance of Organ Pipe Cactus National Monument.Continue another 18 miles to the Visitors Center. Ajo Mountain Road is on the east side of the road.