St. Johns County is located in north-eastern Florida along the Atlantic Coast. In the old days, St. Johns and Escambia County were the two first counties in Florida - and the Suwannee River was the dividing line. Today, St. Johns County contains 609 square miles of land area and 212 square miles of water surface. The county is named after St. John the Baptist. The county seat is St. Augustine, arguably the first European settlement in the United States.

The A1A Scenic Byway runs north/south along the beach in St. Johns County. St. Johns County has seen huge population growth over the last decade because of all the folks flooding in to work in the Jacksonville area. With Ponte Vedra and Pont Vedra Beach, St. Johns County is one of the most affluent counties in the United States.

Interstate 95 and US Highway 1 cross the county north/south.