East Florida

East Florida (Spanish: Florida Oriental) was a colony of Great Britain from 1763 to 1783 and a province of the Spanish Empire from 1783 to 1821. The British gained control over Spanish Florida in 1763 as part of the Treaty of Paris that ended the Seven Years' War. Deciding that the colony was too large to administer as a single unit, British officials divided Florida into two colonies separated by the Apalachicola River: the colony of East Florida, with its capital located in St. Augustine; and West Florida, with its capital located in Pensacola. East Florida was much larger and comprised the bulk of the former Spanish colony and most of the current state of Florida. It had also been the most populated region of Spanish Florida, but before control was transferred to Britain, most residents – including virtually everyone in St. Augustine – left the territory, with most migrating to Cuba.

Britain tried to attract settlers to the two Floridas without much success. The sparsely populated colonies were invited to send representatives to the Continental Congress but chose not to do so, and they remained loyal to Great Britain during the American Revolutionary War. However, as part of the 1783 treaty that ended the American Revolutionary War and marked Britain's defeat, Britain ceded both Floridas to Spain. The two colonies remained separate, and their boundary was shifted eastward to the Suwannee River.

By the early 1800s, Spain had shown little interest in, and limited capacity for, administering either of the two Floridas beyond their capital cities. American settlers entered the territory without authorization, provoking conflict with the Seminoles, a new Native American culture formed largely by Indigenous refugees from the American Southeast. During the War of 1812, American forces occupied West Florida. American settlers calling themselves the "Patriots" declared the short-lived and unrecognized Republic of East Florida at Amelia Island. The U.S. government soon renounced this action and ordered the return of the occupied land to Spain.

Border disputes between the United States and the Seminoles tribes in Florida continued after the war. By 1817, much of Spanish West Florida had been occupied and annexed by the United States; the territory later became parts of Louisiana, Alabama, and Mississippi. After a decade of escalating border disputes and American incursions, Spain ceded both Floridas to the United States in the Adams–Onís Treaty of 1819. The United States formally took possession in 1821, in exchange for renouncing any claims to Spanish Texas. In 1822, all of East Florida and the remaining portions of West Florida were merged into a single Florida Territory, with borders closely resembling those of the present-day state of Florida.