Port St. Lucie is a city in St. Lucie County, Florida, United States. The population of Port St. Lucie was 88,769 at the 2000 census but grew rapidly during the 2000s. In 2009 the State of Florida estimated the City's population at 155,251. Port St. Lucie forms part of a metropolitan area called the Port St. Lucie, Florida Metropolitan Statistical Area that in 2009 was estimated to have 406,296 residents.