Isabela, Puerto Rico, United States [ZonaUrbana]; population was 13,515 in 1990; housing units was 4,546 in 1990; location is 18°30'N 67°1'W; land area is 2.57 square miles (1,646 acres); water area is 1.22 square miles (778 acres); FIPS code is 36478 [SourceCBP]