Nichols Hills, Oklahoma, United States [City]; population was 4,020 in 1990; housing units was 1,869 in 1990; location is 35°33'N 97°33'W; land area is 2.01 square miles (1,286 acres); water area is 0.01 square miles (7 acres); FIPS code is 51800 [SourceCBP]