Etna is a borough in Allegheny County, Pennsylvania, on the Allegheny River, opposite Pittsburgh. It flourished in the past when it was the site of rolling mills, furnaces, steel-mills, galvanized-pipe works, and other manufactures. In 1900, 5,384 people lived in Etna, in 1910. 5,830 lived there, and in 1940, 7,223 lived there. The population was 3,924 at the 2000 census.
Etna was the terminus of the No. 2 Pittsburgh Railways streetcar service from downtown Pittsburgh, closed in 1952. From 1907 until 1931 it was a stop on the interurban Pittsburgh and Butler Street Railway which linked Pittsburgh with Butler, Pennsylvania.
Etna is located at 40°30′1″N 79°56′56″W / 40.50028°N 79.94889°W / 40.50028; -79.94889 (40.500338, -79.948755).