East Florida was originally a part of the Spanish colony of Florida. Under the terms of the Treaty of Paris (1763), which ended the Seven Years' War, Spain ceded all of its territory east and southeast of the Mississippi River to the Kingdom of Great Britain.

Britain divided the territory into two parts, East Florida, with its capital at St. Augustine, and West Florida, with its capital at Pensacola.

Both Floridas remained loyal to Britain during the American Revolutionary War. Spain participated indirectly in the war as an ally of France and captured Pensacola from the British in 1781. In the Treaty of Paris (1783), which ended the war, Britain ceded both Floridas to Spain.

Spain offered favorable terms for acquiring land, which attracted many settlers from the newly formed United States. There were several territorial disputes between the U.S. and Spain, some resulting in military action. Faced with the prospect of losing control, Spain formally ceded all of its Florida territory to the U.S. in exchange for $5,000,000 in 1821 under the Adams-Onís Treaty.

In 1822, the U.S. Congress organized the Florida Territory, and in 1845, Florida was admitted as the 27th state.

See also: West Florida, History of Florida, Spanish colonization of the Americas