According to the United States Census Bureau, the city has a total area of , making Jacksonville the largest city in land area in the contiguous United States; of this, 86.66% () is land and 13.34% () is water. Jacksonville surrounds the town of Baldwin. Nassau County lies to the north, Baker County lies to the west, and Clay and St. Johns counties lie to the south; the Atlantic Ocean lies to the east, along with the Jacksonville Beaches. The city developed along both sides of the St. Johns River. The Trout River, a major tributary of the St. Johns River, is entirely within Jacksonville.