Florida
Florida had become a burden to Spain, which could not afford to send settlers or garrisons. Madrid therefore decided to cede the territory to the United States through the Adams–Onís Treaty, which took effect in 1821. President James Monroe was authorized on March 3, 1821 to take possession of East Florida and West Florida for the United States and provide for initial governance. Andrew Jackson, on behalf of the U.S. federal government, served as a military commissioner with the powers of governor of the newly acquired territory for a brief period. On March 30, 1822, the U.S. Congress merged East Florida and part of West Florida into the Florida Territory.
By the early 1800s, Indian removal was a significant issue throughout the southeastern U.S. and also in Florida. In 1830, the U.S. Congress passed the Indian Removal Act and as settlement increased, pressure grew on the U.S. government to remove the Indians from Florida. Seminoles offered sanctuary to blacks, and these became known as the Black Seminoles, and clashes between whites and Indians grew with the influx of new settlers. In 1832, the Treaty of Payne's Landing promised to the Seminoles lands west of the Mississippi River if they agreed to leave Florida. Many Seminole left at this time.
Polk County, Florida
For around 250 years after Ponce De Leon arrived on the peninsula, the Spanish nominally ruled Florida but established few settlements. In the late 17th century, Florida went through an unstable period in which the French and British ruled the peninsula. By this time, the remnants of early Native Americans joined with refugee Creek Native Americans from Georgia and The Carolinas to form the Seminole Indian Tribe, through a process of ethnogenesis.After the American Revolution, the peninsula briefly reverted to Spanish rule. In 1819, Florida became a U.S. territory as a result of the Adams-Onis Treaty. From the 1830s until 1842, the US conducted the Seminole Wars in an effort to remove the Seminole from the territory. Some were removed to Indian Territory, but others retreated to the Everglades and never surrendered.