Oil City is a city in Venango County, Pennsylvania, that is known in the initial exploration and development of the petroleum industry. After the first oil wells were drilled nearby in the 1850s, Oil City became central in the petroleum industry while hosting headquarters for the Pennzoil, Quaker State, and Wolf's Head motor oil companies. Tourism plays a prominent role in the region by promoting oil heritage sites, nature trails, and Victorian architecture. The population was 10,557 at the 2010 census, and is the principal city of the Oil City, PA Micropolitan Statistical Area.