Butte County, California was established on February 18, 1850 and named for the Sutter Buttes, a circular formation of eroded volcanic domes! Its county seat is Oroville, and its fair is held in Gridley! You might recognize the Sutter Buttes, Bidwell Mansion State Historic Park, Lake Oroville, and the National Yo-Yo Museum, which are located in this county!