The Tuolumne River begins up in the Sierra Nevada and flows through Mariposa County, Tuolumne County, and, finally, Stanislaus County. From its origins to the endpoint flowing into the San Joaquin River, it provides life and an economic source for this entire region. Once a major shipping route, it now provides irrigation water to one of the most agriculturally industrious regions in the world. The history of the Tuolumne River is the story of Stanislaus County and the surrounding areas.