Jacksonville, Florida is 6.7 times larger than Port St. Lucie, Florida.
Area: 1,988 km2 calculated
Jacksonville is the largest city in the U.S. state of Florida by population and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968. Wikipedia
Area: 295 km2 calculated
Port St. Lucie is a city in St. Lucie County, Florida, 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. Wikipedia