Tuolumne County, California

Tuolumne County, officially the County of Tuolumne, is a county in the U.S. state of California. As of the 2010 census, the population was 54,179. The county seat and only incorporated city is Sonora. The county is in the Sierra Nevada region.

The northern half of Yosemite National Park is in the eastern part of this county.

Tuolumne County was founded in 1850.