Lafayette metropolitan area, Louisiana in the context of Lake Charles metropolitan area

Lafayette (/ˌlæfiˈjɛt, ˌlɑːf-/ LA(H)-fee-YET, French: [lafajɛt]) is the most populous city in and the parish seat of Lafayette Parish in the U.S. state of Louisiana, located along the Vermilion River. It is Louisiana's fourth-most populous city with a 2020 census population of 121,374; the consolidated city-parish's population was 241,753 in 2020. The Lafayette metropolitan area was Louisiana's third largest metropolitan statistical area with a population of 478,384 at the 2020 census. The Acadiana region containing Lafayette is the largest population and economic corridor between Houston, Texas and New Orleans.

Originally established as Vermilionville in the 1820s and incorporated in 1836, Lafayette developed as an agricultural community until the introduction of retail and entertainment centers, and the discovery of oil in the area in the 1940s. Since the discovery of oil, the city and parish have had the highest number of workers in the oil and natural gas industry in Louisiana as of 2018. With the issuance of a bond ordinance for a series of roads connecting nearby settlements, the establishment of the University of Louisiana System's Lafayette campus, and the continued diversification of its economy, Lafayette and its metropolitan area have experienced population growth since the 1840 census and was promptly nicknamed "The Hub City." The city and parish of Lafayette are also known as the "Heart of Acadiana."

Erath /ˈiːræθ/ is a town in Vermilion Parish, Louisiana, United States. The population was 2,114 at the 2010 census, and 2,030 at the 2020 population estimates program. It is part of the Abbeville micropolitan statistical area and the Lafayette metropolitan area.

St. Martin Parish (French: Paroisse de Saint-Martin) is a parish located in the U.S. state of Louisiana, founded in 1811. Its parish seat is St. Martinville, and the largest city is Breaux Bridge. At the 2020 census, the population was 51,767. St. Martin Parish is part of the Lafayette metropolitan area in the region of Acadiana, along the Gulf Coast.