Coamo is a small town nestled in a valley about 10 miles (16 km) east of Ponce (about 30 minutes by car). It was named "San Blas Illescas de Coamo" by its first settlers. San Blas was the Catholic saint who remains the town's patron. Illescas is the Spanish town where the town founders originated (nowadays in Toledo province, Castile-La Mancha, Spain).
There are several theories regarding the origin of the word "Coamo". Some think it comes from an indigenous word that means "valley" but it is also plausible that Coamo derives its name from Coamex (or Coamey), who was a celebrated local cacique (or "chieftain" in the Taino language). Archeological digs near the region have produced some of the best examples of the island's pre-Columbian cultural artifacts.
Founded on July 15, 1579, Coamo is the third-oldest settlement of the island's post-Columbian period (after San Juan in the north and San Germán in the west). By 1582, there were twenty families living in Coamo, in the same area where the Tainos had had their village of Guayama. Coamo officially became a town in 1616, and was given the title of "Villa" by Spanish Royal Decree in 1778.
Coamo was the administrative center that encompassed most of the southern half of the island during the early colonial period. As the agricultural and sugar industries grew and became the mainstays of the colony's economy, the province would eventually subdivide into several distinct municipalities, and the administrative center of the region would later shift west to the coastal town of Ponce.