Butler County, formed in 1800, prospered as a result of various industries, including coal mining, farming, and lumbering. A successful oil industry transformed the county into a bustling, thriving community and introduced railroads, which opened up the area to other parts of the United States. Companies such as Standard Steel Car and Columbia Steel employed thousands. The introduction of streetcars in 1900 further drew people into the area, helping to develop towns such as Mars, Zelienople, and Evans City. Butler County continued to evolve with the construction of one of the first airports in the Pittsburgh area, the Pittsburgh-Butler Airport in the Nixon area of Penn Township. Butler County celebrates the history of the area through two hundred vintage postcards, including rare images featuring Roy Kanbenshue flying his dirigible, the Goosetown Gang, and Slippery Rock State Normal School.