Mokelumne City arose as a rival trade centre to Stockton in 1850, near the mouth of the Cosumnes River, at the confluence of the Cosumnes and Mokelumne Rivers. Sloops built there ran direct to San Francisco. It rose to poll 172 votes, but the Great Flood of 1862 so ravaged the place that it never recovered.
The site of the former city is located about 14 miles north-west of Lodi, California. It is 200 feet north of the intersection of Cameron Road and Thornton Road, 3 miles north of Thornton, California.