Yaphank, New York, United States [CDP]; population was 4,637 in 1990; housing units was 1,506 in 1990; location is 40°50'N 72°56'W; land area is 13.67 square miles (8,751 acres); water area is 0.11 square miles (73 acres); FIPS code is 83426 [SourceCBP]