St. Petersburg is a city in Pinellas County, Florida, United States. As of the 2015 census estimate, the population was 257,083, making it the fifth-most populous city in Florida and the largest in the state that is not a county seat. St. Petersburg is the second-largest city in the Tampa Bay Area, after Tampa. Together with Clearwater, these cities comprise the Tampa–St. Petersburg–Clearwater Metropolitan Statistical Area, the second-largest in Florida with a population of around 2.8 million.