Monroe (historically French: Poste-du-Ouachita) is the eighth-largest city in the U.S. state of Louisiana. It is the parish seat of Ouachita Parish. In the official 2010 census, Monroe had a population of 48,815. The municipal population declined by 8.1 percent over the past decade; it was 53,107 in the 2000 census. After a recheck in 2019, the Census Bureau changed the 2010 population from 48,815 to 47,294.
Monroe is the principal city of the Monroe Metropolitan Statistical Area, which includes the parishes of Ouachita and Union. The two-parish area had a total population of 170,053 in 2000 and an estimated population of 172,275 as of July 1, 2007. The larger Monroe-Bastrop Combined Statistical Area is composed of both the Monroe Metropolitan Statistical Area and the Bastrop Micropolitan Statistical Area. The CSA had a population of 201,074 in 2000. Monroe and the neighboring city of West Monroe (pop.