West Florida (Spanish: Florida Occidental) was a region on the northern coast of the Gulf of Mexico that underwent several boundary and sovereignty changes during its history. As its name suggests, it was formed out of the western part of former Spanish Florida (East Florida formed the eastern part, with the Apalachicola River the border), along with lands taken from French Louisiana; Pensacola became West Florida's capital. The colony included about two thirds of what is now the Florida Panhandle, as well as parts of the modern U.S. states of Louisiana, Mississippi, and Alabama.

Great Britain established West and East Florida in 1763 out of land acquired from France and Spain after the Seven Years' War. As the newly acquired territory was too large to govern from one administrative center, the British divided it into two new colonies separated by the Apalachicola River. British West Florida included the part of formerly Spanish Florida which lay west of the Apalachicola, as well as parts of formerly French Louisiana; its government was based in Pensacola. West Florida thus encompassed all territory between the Mississippi and Apalachicola Rivers, with a northern boundary which shifted several times over the subsequent years.

Both West and East Florida remained loyal to the British crown during the American Revolution, and served as havens for Tories fleeing from the Thirteen Colonies. Spain invaded West Florida and captured Pensacola in 1781, and after the war Britain ceded both Floridas to Spain. However, the lack of defined boundaries led to a series of border disputes between Spanish West Florida and the fledgling United States known as the West Florida Controversy.

Because of disagreements with the Spanish government, American and English settlers between the Mississippi and Perdido rivers declared that area as the independent Republic of West Florida in 1810. (None of the short-lived Republic lay within the borders of the modern U.S. state of Florida; it comprised the Florida parishes of today's Louisiana.) Within months it was annexed by the United States, which claimed the region as part of the Louisiana Purchase of 1803. In 1819 the United States negotiated the purchase of the remainder of West Florida and all of East Florida in the AdamsOns Treaty, and in 1822 both were merged into the Florida Territory.

The Spanish colonization of the Americas began under the Crown of Castile and was spearheaded by the Spanish conquistadors. The Americas were invaded and incorporated into the Spanish Empire, with the exception of Brazil, British America, and some small regions of South America and the Caribbean. The crown created civil and religious structures to administer the vast territory. The main motivations for colonial expansion were profit through resource extraction and the spread of Catholicism through indigenous conversions.

Beginning with the 1492 arrival of Christopher Columbus in the Caribbean and gaining control over more territory for over three centuries, the Spanish Empire would expand across the Caribbean Islands, half of South America, most of Central America and much of North America. It is estimated that during the colonial period (1492–1832), a total of 1.86 million Spaniards settled in the Americas, and a further 3.5 million immigrated during the post-colonial era (1850–1950); the estimate is 250,000 in the 16th century and most during the 18th century, as immigration was encouraged by the new Bourbon dynasty.By contrast, the indigenous population plummeted by an estimated 80% in the first century and a half following Columbus's voyages, primarily through the spread of disease, forced labor and slavery for resource extraction, and missionization. This has been argued to be the first large-scale act of genocide in the modern era.In the early 19th century, the Spanish American wars of independence resulted in the secession and subsequent division of most Spanish territories in the Americas, except for Cuba and Puerto Rico, which were lost to the United States in 1898, following the Spanish–American War. The loss of these territories ended Spanish rule in the Americas.