A gentle and moderate drive of sixty miles from the town of Sonora along California Highway 108, leads to Sonora Pass at 9,628 feet in elevation at the intersection of Tuolumne and Mono Counties. On the eastern side, the road becomes very steep.  The Sonora Pass grade is at 7% to 26%, the steepest grade in the Sierra Nevada and is twenty four miles of continuous switchbacks, down into the high desert of Nevada.