Coordinates: 29°44′N 90°06′W / 29.733°N 90.100°W / 29.733; -90.100. Jefferson Parish (French: Paroisse de Jefferson) is a parish in the U.S. state of Louisiana. As of the 2010 census, the population was 432,552. The parish seat is Gretna. Jefferson Parish is included in the New Orleans-Metairie, LA Metropolitan Statistical Area. Jefferson Parish was less affected by Hurricane Katrina in 2005 and has rebounded at a more rapid pace than neighboring Orleans Parish.