Port St. Lucie is a city located in the U.S. state of Florida. It is within St. Lucie County and the most populous municipality in the county. It has a total area of 120.51 square miles at 27°16′33″N 80°21′18″W. The elevation is 16 feet above sea level. As of the 2010 census data, it had a total population of 164,603. The population density was 1,557.18/sq mi. Port St. Lucie was incorporated on April 27, 1903.