The Colusa County Courthouse, in Colusa, California was erected in 1861. This Federal/Classic Revival style building is the oldest remaining courthouse in the Sacramento Valley. The "Southern" style reflects the county's heritage and states' rights sympathies during the American Civil War, largely due to the influence of the local newspaper editor Will S. Green. In its early years, the courthouse also served as a center for cultural, social, and religious activities. The courthouse is California Historical Landmark #890.