what county is port st. lucie florida in
City of Port St. Lucie. Port St. Lucie is a city in St. Lucie County, Florida, in the United States. The population of Port St. Lucie was 164,603 at the 2010 census due to its rapid growth during the 2000s. In 2013 the state of Florida estimated the city's population at 171,016. Port St. Lucie forms part of a metropolitan area called the Port St. Lucie, Florida Metropolitan Statistical Area that in 2013 was estimated to have 438,095 residents.