Sanford is a city in the central region of the U.S. state of Florida and is the county seat of Seminole County. Known as the "Historic Waterfront Gateway City," Sanford sits on the southern shore of Lake Monroe at the head of navigation on the St. Johns River. The city sits approximately 20 miles (32 km) northeast of Orlando. As of the 2010 census, the city had a population of 53,570. The Orlando Sanford International Airport, which is in the heart of the town, functions as the secondary commercial airport for international and domestic carriers in the Orlando metropolitan area.