The history of Leon County, Florida, much like the History of Tallahassee, dates back to the settlement of the Americas. Beginning in the 16th century, the region was colonized by Europeans, becoming part of Spanish Florida. In 1819, the Adams–Onís Treaty ceded Spanish Florida, including modern-day Leon County, to the United States. Named for Spanish explorer Juan Ponce de León, Leon County became an official U.S. county in 1824; the American takeover led to the county's rapid expansion as growing numbers of cotton plantations began to spring up nearby, increasing Leon County's population significantly.