Opelousas County, Louisiana
The city of Opelousas was founded in 1720 and is Louisiana's 3rd oldest city. The city served as a major trading post between New Orleans and Natchitoches in the 18th and 19th centuries.
To encourage settlement in the area, Governor O'Reilley issued a land ordinance to allow settlers in the frontier of the Opelousas area to acquire land grants. The first official land grant was made to a settler in the Opelousas area in 1782. The area was acquired by the United States as part of the Louisiana Purchase in 1803, and in 1805 became the seat of the newly formed St. Landry Parish, also known as the Imperial Parish of Louisiana.
The County of Opelousas became St. Landry in 1805. The city of Opelousas became the parish seat.
The name Opélousas has been given many meanings, but the long accepted one is "Black leg." Some people think that members of the tribe painted their legs a dark color. One theory is that the Opelousas' legs were stained as they waded in stagnant waters to hunt and fish. Simon le Page Du Prat, who lived in Louisiana from 1718 to 1734, eight years of which he spent living among the Indians, said the Opelousas lived just west of two small lakes, thought to be "Leonard Swamp," east of Opelousas. This was the westernmost channel of the Mississippi River in prehistoric times. The waters of the lake were black because of the great number of leaves covering the bottom. More recently, Hugh Singleton, a student of the Attakapas language, has advanced the theory that the name comes from the Attakapas words Ap (at this place) and Elush (it is very hot). Singleton says he thinks that early Spaniards visiting the area changed the spelling of the name from Ap Elush to Opelus and then named the people who lived there Opelusas, without the "o." Next came the French, who added the "o" to create the spelling Opélousas.
Source: wiki -- Opelousas