There are 13 US Post Offices in Tuolumne County serving a total of 54,136 residents equating to 4,164 residents per post office. It's estimated that approximately 86,407 packages are handled across the 13 county post offices annually. Tuolumne County (/tu\u02d0\u02c8\u0252l\u0259mi\u02d0/ \"To All o' Me\", with a silent N), officially the County of Tuolumne, is a county in the U.S. state of California. As of the 2010 census, the population was 55,365. The county seat and only incorporated city is Sonora. Tuolumne County comprises the Sonora, CA Micropolitan Statistical Area. The county is in the Sierra Nevada region. The northern half of Yosemite National Park is located in the eastern part of the county."