 The population density was 3,371.7 people per square mile (1,301.8/km²).There were 782,009 housing units at an average density of 1,349.6 per square mile (521.1/km²).If the city of Houston were a U.S. state, it would rank 36th in population—its estimated 2.01 million residents in 2004 placed it behind Nevada and ahead of New Mexico.