Gretna is the second-largest city in, and parish seat of, Jefferson Parish, Louisiana, United States. Gretna lies on the west bank of the Mississippi River, just east and across the river from uptown New Orleans. It is part of the New Orleans–Metairie–Kenner Metropolitan Statistical Area. The population was 17,736 at the 2010 census.
Gretna is located at 29°54′59″N 90°3′15″W (29.916459, -90.054260) and has an elevation of 0 feet (0 m) behind the levee along the Mississippi River.
According to the United States Census Bureau, the city has a total area of 3.9 square miles (10 km2), of which 3.5 sq mi (9.1 km2) is land and 0.4 sq mi (1.0 km2) (9.33%) is water.
According to the history published by the city, Gretna's history can be traced to a plantation established by Jean de Pradel by 1750 (when the plantation house, Monplaisir, was built). By 1813, the plantation had passed into the hands of one Francois Bernoudy. John McDonogh, also spelled John McDonough, then a resident of New Orleans, bought the establishment, moved into the house and founded a settlement in 1815, that would be named McDonoughville. He subdivided the rest of the former plantation into regular city lots and 30-arpent farming strips. McDonoughville thus became the first subdivision in Jefferson Parish.