Harquahala Mountain Back Country Byway

"The Search for the Solar Constant"

A challenging drive to the top of the highest mountain in Southwestern Arizona leads to the site of early scientific research on solar energy.


80 miles west of Phoenix or 40 miles southwest of Wickenburg. From Phoenix, take I-10 west to the Salome Road Exit (50 miles). Turn right and follow for 9.6 miles to Eagle Eye Road. Turn right and go 8.5 miles to a dirt road which heads north towards the summit.  Or travel north on I-17 to the Carefree Highway exit, turn left on H-74, heading west past Lake Pleasant, to H-60. Turn right and head northwest to Wickenburg. From Wickenburg, continue on H-60 (which veers west), to Aguila. Turn right, heading south, on Eagle Eye Road 18.5 miles to the dirt road heading 10.5 miles north climbing the summit.  (See Map)


 The Harquahala Mountain Summit Road offers something for everyone! The road itself is rugged and challenging for OHV enthusiasts. For the nature lover it has beautiful Sonoran Desert scenery with blooming flora March through May and distinct ecosystem variations can be seen with changes in elevation. In addition to the typical desert reptiles and critters which can be encountered, bighorn sheep may also be spotted. For the scenic enthusiast, the summit is the highest point in southwest Arizona with breathtaking 360 degree vistas. For hikers, a pack trail leads from the summit down the mountain through the Harquahala Wilderness Area designated in The Arizona Desert Wilderness Act of 1990. The trail has several difficult and steep portions. For the history buff, the drive displays old mining debris, shafts and stone houses from earlier miners. The grand finale is realized at the summit with the Harquahala Peak Observatory. The observatory was built by the Smithsonian in 1920 to measure and record solar activity. It was abandoned in 1925 and in 1975 was listed on the National Register of Historic Places and has since been stabilized.

Best Season

All year, but it is best in the fall, winter and spring. It is very hot in the summer. Do not drive if snow has fallen on the summit or if lightning threatens. It is advised that you contact BLM's Hassayampa Field Office or the National Weather Service for current road conditions and weather forecasts.



In case you encounter unexpected trouble:

  • Nearest Hospital: Wickenburg
  • Nearest Law Enforcement: Wickenburg


 Hassayampa Field Office 
21605 N. 7th Avenue
Phoenix, AZ 85027-2929
Phone: (623) 580-5500
Fax: (623) 580-5580
Field Manager:  Rem Hawes
Hours:  7:30 a.m. – 4:15 p.m., M-F