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.
Cuban Americans
Before the Louisiana Purchase and the Adams–Onís Treaty of 1819, Spanish Florida, and when divided during British occupation, East Florida and West Florida, including what is now Florida and the Gulf Coast west to the Mississippi River were provinces of the Captaincy General of Cuba (Captain General being the Spanish title equivalent to the British colonial Governor). Consequently, Cuban immigration to the U.S. has a long history, beginning in the Spanish colonial period in 1565 when St. Augustine, Florida was established by Pedro Menéndez de Avilés, and hundreds of Spanish-Cuban soldiers and their families moved from Cuba to St. Augustine to establish a new life.