Aren’t the reasons for Florida’s borders pretty obvious? Still, how come two different straight lines define Florida’s northern border? And why, at the eastern end of its northern border, does the boundary abandon its straight line and dip down, then jog up?
Florida was originally part of Spain’s colonial territories in the New World, an empire that included all those South and Central American countries that speak Spanish today, along with what is now the western United States and up the Pacific coast as far as Vancouver.
Florida’s Northern Border
When England chartered the colony of Georgia in 1732, its border with Spanish Florida extended only to the Altamaha River, which empties into the ocean near the present-day town of Brunswick. But Spain claimed possession of all the land up to the Savannah River—the southern boundary of the Carolina Colony. (Figure 54)
The dispute eventually erupted into war. Georgia’s colonists defeated the Spanish in the Battle of Bloody Marsh on St. Simons Island in 1739, and in so doing ended Spanish claims north of the St. Marys River. To this day, the St. Marys River serves as the eastern end of the northern border of Florida.
While the St. Marys River provides a natural boundary between Georgia and Florida from the Atlantic Ocean to the Okefenokee Swamp, it is also a bit erratic. About 30 miles inland, the river takes a 90-degree turn to the south, then after about another 30 miles executes a U-turn. This accounts for the irregular jog in Florida’s northeast corner. (Figure 55)
FIG. 54 Florida and Georgia’s Conflicting Claims—1732
FIG. 55 Battle of Bloody Marsh Border Adjustments—1739
Since the residents of the Okefenokee Swamp were mostly alligators, birds, and bugs, the Georgians and Spaniards agreed that a straight-line border through the swamp would suffice. That line proceeds from the headwaters of the St. Marys River in the eastern side of the swamp westward to the convergence of the Flint River and the Chattahoochee River. Like the St. Marys River, this border, too, has remained in effect, a vestige of the uneasy relationship between 18th-century Spaniards and their colonial American counterparts.
But upon reaching this juncture, the border suddenly jumps 20 miles up the Chattahoochee River, then heads due west. (Figure 56) What happened here?
This leap to the north is an artifact that is older than the boundary agreed upon between Spain and the British colonists at Georgia. The line that resumes 20 miles north follows the 31st parallel, as specified in the first royal charter creating the Carolina Colony in 1663, nearly seventy years before the founding of Georgia. These boundaries are today the northern border of Florida.
FIG. 56 The Components of Florida’s Northern Border
Florida’s Western Border
Originally, the western border of Spanish Florida was the Mississippi River. Not long after the American Revolution, that changed. In 1810, marking a further sign of Spain’s weakening power, the young United States seized the westernmost portion of Spanish Florida, a chunk of land that extended from the Mississippi River to the Pearl River. Having purchased the western side of the Mississippi in the 1803 Louisiana Purchase, the new nation felt it was vital that it possess both sides of the river to ensure unchallenged access to the Gulf of Mexico and the sea.
A second seizure of land in western Florida took place in 1813, justified on the basis of Spain’s support of the British in the ongoing War of 1812. This time the Americans took the adjacent chunk of land, eastward to the Perdido River. This seizure included Mobile Bay, providing the United States a valuable port. (Figure 57) Today’s western edge of Florida remains the Perdido River, just west of Pensacola.
FIG. 57 American Acquisitions from Spanish Florida
Over the next ten years, Spain would lose virtually all of its possessions in the Americas. Recognizing the need to retreat, Spain released its remaining claims to Florida to the United States in the Adams-Onis Treaty (1819).