Colusa County is a county located in the U.S. state of California. As of the 2020 census, the population was 21,839. The county seat is Colusa. It is in the northern Sacramento Valley, northwest of the state capital, Sacramento.
Country: United States
State: California
Region: Sacramento Valley
Incorporated: February 18, 1850
Named for: Rancho Colus
County seat: Colusa
Largest city: Colusa (population) · Williams (area)