Cabo Rojo (Spanish pronunciation: [ˈkaβo ˈroxo]) is a municipality situated on the southwest coast of Puerto Rico and forms part of the San Germán–Cabo Rojo metropolitan area as well as the larger Mayagüez–San Germán–Cabo Rojo Combined Statistical Area.
The area near Las Salinas (salt flats) has been inhabited since 30 BC and AD 120 according to archaeological evidence. Punta Ostiones, listed in the National Register of Historic Places as an archeological site, was home to a large group of Archaic Indians.
Despite the threat of pirates and natives, the Spanish settled the area of Los Morrillos around 1511. By 1525, salt mining was an important industry in the area. In 1759 the first request to establish itself as a town was denied. Cabo Rojo was founded on December 17, 1771 by Don Nicolás Alfonso Ramírez de Arellano y Martínez de Matos, a descendant of Spanish royalty and nobility, with the approval of Governor and Captain General Miguel de Muesas. According to Fray Iñigo Abbad y Lasierra by the end of the 18th century, Cabo Rojo had a population of 1,215 people.
Cabo Rojo (Red Cape in English) derives its name from both the reddish color of its salt-flats and the reddish tint that characterizes the seaside cliffs along its southern coast. According to legend, the name was given by Christopher Columbus himself. The first church, founded in 1783, was called San José. The present-day main Catholic church is called San Miguel Arcángel Church located in the town's square.