Densmore Tank Cars. The first functional railway oil tank car was invented and constructed in 1865 by James and Amos Densmore at nearby Miller Farm along Oil Creek. It consisted of two wooden tanks placed on a flat railway car; each tank held 40-45 barrels of crude oil. A successful test shipment was sent in Sept., 1865 to New York City. By 1866, hundreds of tank cars were in use. The Densmore Tank Car revolutionized the bulk transportation of crude oil to market.