St. Augustine, Florida's Colonial Capital

East Florida (Spanish: Florida Oriental) was a colony of Great Britain from 1763 to 1783 and a province of Spanish Florida from 1783 to 1821. East Florida was founded as a colony by the British colonial government in 1763; it consisted of peninsular Florida, with its western boundary at the Apalachicola River. Its capital was St. Augustine, which had been the capital of Spanish La Florida.

Britain formed East and West Florida out of territory it had received from Spain and France following the French and Indian War (the Seven Years' War). Finding its new acquisitions in the southeast too large to administer as a single unit, the British divided them into two colonies separated by the Apalachicola River. East Florida comprised the bulk of what had previously been the Spanish territory of Florida.

Britain ceded both Floridas to Spain following the American Revolutionary War. Spain maintained them as separate colonies, although the majority of West Florida was gradually occupied and annexed by the United States from 1810 to 1813. Spain ceded East Florida and the remainder of West Florida to the US in the Adams–Onís Treaty of 1819. In 1822 the United States organized them as a single unit, the Florida Territory.

Under the terms of the 1763 Treaty of Paris, which ended the Seven Years' War (the French and Indian War), Spain ceded Spanish Florida to Britain. At the same time, Britain received all of French Louisiana east of the Mississippi River, with the exception of New Orleans, from France. Determining the new territory too large to administer as one unit, Britain divided its new southeastern acquisitions into two new colonies separated by the Apalachicola River: East Florida, with its capital in the old Spanish city of St. Augustine, and West Florida, with its capital at Pensacola.