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.
Sanford, Florida
The Mayaca or Jororo Indians inhabited the shores of Lake Monroe at the time of European contact. By 1760, however, war and disease had decimated the tribe, which would be replaced by the Seminole Indians. Florida was acquired by the United States from Spain in 1821, but the Seminole Wars would delay settlement. In 1835, the Seminoles burned the port of Palatka on the St. Johns River, then the major artery into Central Florida from the East Coast. Consequently, an army garrison was established upstream, on the southern side of Lake Monroe near a trading post. Called Camp Monroe, the log breastwork was attacked on February 8, 1837. It would be strengthened and renamed Fort Mellon in honor of Captain Charles Mellon, the sole American casualty.General Zachary Taylor had a road built connecting a string of defenses from Lake Monroe to Fort Brooke (now Tampa). The town of Mellonville was founded around Fort Mellon in 1842 by Daniel Stewart. In 1845, Florida became a U.S. state, and Mellonville became county seat of Orange County, formerly called Mosquito County with its county seat across the lake at Enterprise. Orange groves were planted, with the first fruit packing plant built in 1869. In 1870, "General" Henry Shelton Sanford bought to the west of Mellonville and laid out the community of Sanford. Believing it would become a transportation hub, he called it "The Gateway City to South Florida."