ETNA, a borough of Allegheny county, Pa., U.S.A., 2m. N. of Pittsburgh, on the west bank of the Allegheny river. It is served by the Baltimore and Ohio, the Etna and Montrose and the Penn sylvania railways. The population was 6,341 in 1920, and was 7,493 in 193o by the Federal census. It is an important manufac turing suburb of Pittsburgh, producing iron, steel, brass, enamelled ware and various other commodities. The borough (at first called Steuart's Town) was incorporated in 1869. Its industrial history dates from 18 20, when a small factory was built to make scythes and sickles. Natural gas was piped in from Butler county to serve as fuel for the early iron mills.