The Everglades are a natural region of subtropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee. Water leaving the lake in the wet season forms a slow-moving river 60 miles (97 km) wide and over 100 miles (160 km) long, flowing southward across a limestone shelf to Florida Bay at the southern end of the state. The Everglades are shaped by water and fire, experiencing frequent flooding in the wet season and drought in the dry season. Writer Marjory Stoneman Douglas popularized the term "River of Grass" to describe the sawgrass marshes, part of a complex system of interdependent ecosystems that include cypress swamps, the estuarine mangrove forests of the Ten Thousand Islands, tropical hardwood hammocks, pine rockland, and the marine environment of Florida Bay.
Human habitation in the southern portion of the Florida peninsula dates to 15,000 years ago. Two major tribes eventually formed in and around Everglades ecosystems: the Calusa and the Tequesta. After coming into contact with the Spanish in the late 16th century, both tribes declined gradually during the following two centuries. The Seminoles, a tribe of Creeks who assimilated other peoples into their own, made their living in the Everglades region after being forced there by the U.S. military in the Seminole Wars of the 19th century.