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.

Fort Harrison was a United States military post that existed along the west coast of Florida during the Second Seminole War, on a site which now lies within the city of Clearwater. It was named after William Henry Harrison, the then newly inaugurated President of the United States.