Guayanilla (gwah-yah-NEE-yah), town (1990 pop. 21,581), S P.R., 10 mi/16 km W of Ponce. Petrochemicals; thermoelectric plants produce more than 1/2 electric power used on isl. Oil refinery. Playa de Guayanilla (port) is 1.5 mi/2.4 km SE. First settled 1511.