GRETNA, a city of south-eastern Louisiana, U.S.A., on the Mississippi river, opposite New Orleans; the capital of Jefferson parish. It is served by the Missouri Pacific, the Southern Pacific, and the Texas and Pacific railways, and by the industrial belt line which makes connections between all the roads entering New Orleans. The population was 7,197 in 1920 (27% negro) and was in 193o by the Federal census. There are large oil refineries and other industrial plants. The city was incorporated in 1913.