Placer County is a county located in the U.S. state of California. As of the 2010 census, the population was 348,432. The county seat is Auburn. The county borders Yuba County and Nevada County to the north, the state of Nevada to the east, El Dorado County and Sacramento County to the south, and Sutter County to the west.
Placer County is included in the Sacramento-Roseville-Arden-Arcade, CA Metropolitan Statistical Area. It is located in both the Sacramento Valley and Sierra Nevada regions, in what is known as the Gold Country. It stretches from the suburbs of Sacramento to Lake Tahoe and the Nevada border.