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.
History of Pensacola, Florida
On March 3, 1845, Florida was admitted to the Union as the 27th state. Its admission had been slowed as the United States struggled to remove the Seminole Indians. After three Seminole Wars, it defeated some, forcing their removal to Indian Territory in what is now Oklahoma. The remaining Seminole had retreated to the Everglades and were never defeated. Due to rising tensions over slavery, Congress had decided not to alter the balance between slave and free states. Florida's admission was delayed until a free territory was ready for admission as a state. It was admitted the same year as Iowa. North Florida, including the Panhandle, remained the most populated part of the state.