city, Venango county, northwestern Pennsylvania, U.S., on a bend of the Allegheny River at the mouth of Oil Creek, 70 miles (113 km) north of Pittsburgh. Founded in 1860 on the site of a Seneca Indian village, it burgeoned as an oil centre after the drilling of the world's first oil well (August 27, 1859) at Titusville, about 16 miles up Oil (petroleum) Creek. Incorporated as a borough in 1862, it became a city in 1871 after merging with Venango City. Oil City was the shipping point for crude oil from Oil Creek fields and reached a high point between 1860 and 1870 with riverboats transporting millions of barrels to Pittsburgh.

The production, refining, and distribution of oil and its products remains the leading industry. Natural-gas fields are nearby. Manufactures include steel barrels, plastic containers, specialty alloys, and hardwood, machine-shop, and chemical products. Oil Creek State Park, Drake Well Park (site of the world's first oil well), and Pithole (a ghost oil town) are nearby. Pop. (1990) 11,949; (2000) 11,504.