St. Petersburg is a city in Pinellas County, Florida, United States. As of the 2020 census, the population was 258,308, making it the fifth-most populous city in Florida and the second-largest city in the Tampa Bay Area, after Tampa. It is the largest city in the state that is not a county seat (the city of Clearwater is the seat of Pinellas County). Along with Clearwater, these cities are part of the Tampa–St. Petersburg–Clearwater Metropolitan Statistical Area, the second-largest in Florida with a population of around 2.8 million. St. Petersburg is on the Pinellas peninsula between Tampa Bay and the Gulf of Mexico, and is connected to mainland Florida to the north.