Yolo County, officially the County of Yolo, is a county located in the northern portion of the U.S. state of California. Yolo County was one of the original counties of California, created in 1850 at the time of statehood. As of the 2020 census, the population was 216,403. Its county seat is Woodland. Yolo County is included in the Greater Sacramento metropolitan area and is located in the Sacramento Valley.