Oroville is the county seat of Butte County, California, United States. The population was 15,506 at the 2010 census, up from 13,004 in the 2000 census. Oroville is considered the gateway to Lake Oroville and Feather River recreational areas. The city of Oroville has recently annexed two locations in South Oroville, areas A and B, which have a combined population of 2,725 people. The U.S. Census Bureau estimated the population of the city to be 17,996 as of January 1, 2016, up 1,908 people or 11.9 percent since 2010. The Berry Creek Rancheria of Maidu Indians of California is headquartered here.Oroville is located off of State Route 70, and is in close proximity to State Route 99, which connects Butte County with Interstate 5. Chico, California is located about 25 minutes north of the city, and Sacramento lies about an hour south.