The Everglades is southern Florida’s vast flooded grassland, shaped less by topography than by slow sheetflow from Lake Okeechobee toward Florida Bay across porous limestone. This hydrology created a broad, shallow river whose seasonal floods and droughts governed plants, wildlife, and aquifer recharge. Human presence reaches back about 15,000 years, and the region was later associated with the Calusa, Tequesta, and Seminole, who used its terrain to resist U.S. removal. From the mid-19th century, drainage and flood-control projects transformed the marsh for cities and agriculture, damaging habitat and water quality. By the late 20th century, the Everglades had become a major focus of environmental protection and restoration.