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 most populous city in the state that is not a county seat. It is the second-most populous city in the Tampa Bay area, which is the second-largest metropolitan area in Florida with a population of around 2.8 million.

Pinellas County is a county located on the west central coast of the U.S. state of Florida. As of the 2020 census, the population was 959,107, which makes it the seventh-most populous county in the state. It is also the most densely populated county in Florida, with 3,491 residents per square mile. The county is part of the Tampa–St. Petersburg–Clearwater Metropolitan Statistical Area. Clearwater is the county seat. St. Petersburg is the largest city in the county, as well as the largest city in Florida that is not a county seat.