Etna is a borough in Allegheny County, Pennsylvania, United States, located across the Allegheny River from Pittsburgh. The population was 3,437 at the 2020 census. It is a suburb in the Pittsburgh metropolitan area. Etna was named after the Sicilian volcano Mount Etna, an allusion to blast furnaces, steel mills, galvanized-pipe works, and other manufacturers located there. Historically, it was a steel town with a blue-collar community.