A portion of what was later to become a section of the Sonora-Mono Road was built in 1852 from Sonora to what is now called Confidence. The road was built by the Tuolumne County Water Company in connection with its project on the South Fork of the Stanislaus River to bring water for the working of the gold bearing placers in the Columbia district. A portion of the original road route is still used from Sonora to The Dardanelles.
http://mysierramountaintimes.com/2009/07/travel-through-time-the-history-of-sonora-pass-by-wayne-kirkbride/