Presettlement Florida had a variety of open habitats, including grasslands and savannas. This study examined the historic distribution of the Florida grasslands using U.S. General Land Office land surveys made during the 19th century. All survey maps with areas labeled “prairie” or “savanna” were compiled into a composite map. A total of 791,140 ha of prairies and 15,820 ha of savanna were shown on the maps. The most extensive prairies were located in central Florida stretching from the west coast of Lake Okeechobee into Hillsboro and Manatee counties. Patches of prairie and savanna extended north into Clay County. South of Lake Okeechobee, prairies were found in the Big Cypress Swamp, along the western edge of the Everglades and along the eastern coast. Surveyor's notes and historical documents were then used to find additional references to grasslands. These references indicate that there were extensive prairies and savannas in the northern part of the peninsula and in the panhandle. Areas with prairie and savanna were compared to soil descriptions found in county soil surveys by the U.S. Department of Agriculture. Soils typical of forested areas (spodosols and alfisols) were more common in Florida prairies and savannas than mollisol soils that are characteristic of grasslands. The soil data, in addition with the proximity of prairies to pine forests, supports the hypothesis that these ecosystems are determined more by topography, fire frequency and flooding patterns than by soil type.