The Río Grande de Añasco is a river in western Puerto Rico. Its source is in the Cordillera Central mountain range west of Adjuntas, and it flows about westward to its mouth on the Mona Passage north of Mayagüez. The river flows through the municipalities of Mayagüez, Añasco, San Sebastián and Las Marías. The taínos called it Río Guaorabo. History In the 1898 Military Notes on Puerto Rico by the U.S. it is written that the "Añasco River is formed by the Lares Mountain ridge. It rises in the eastern extremity of the mountains called Tetas de Cerro Gordo, flowing first northwest, and then west, through the town of its name and thence to the sea." It is spanned by the Puente de Añasco, a bridge listed on the National Register of Historic Places. See also Puente de Añasco: NRHP listing in Añasco and Mayagüez, Puerto Rico List of rivers of Puerto Rico References Further reading Añasco River. The Columbia Gazetteer of North America. Columbia University Press, 2000. (Available online.) External links USGS Hydrologic Unit Map – Caribbean Region (1974) Flooding from Río Grande de Añasco during Hurricane Maria in 2017 Rivers of Puerto Rico Añasco, Puerto Rico Mayagüez, Puerto Rico