From the start, Jefferson and his administration, as well as most people who lived along the Gulf Coast, were under the impression that Spain had ceded "the Floridas" to France, along with New Orleans and its sprawling northwestern suburbs. "West Florida" lay south of the 31st parallel between the Perdido River and the Mississippi; "East Florida" extended from the Perdido River along the Gulf Coast to Tampa Bay.
In 1804 Congress authorized the collection of taxes in West Florida, and in 1810 President James Madison simply proclaimed that area to be part of the Louisiana Purchase. By 1817 the tract had been divided between Mississippi and Alabama, temporarily satisfying some Southern settlers' needs for convenient seaports.
Two years later, after Andrew Jackson and his soldiers captured Pensacola, Spain was easily persuaded to cede the rest of that part of the continent to the United States. And good riddance it was. Rife with renegade whites, vengeful Indians, runaway slaves, testy soldiers in vulnerable forts, and a few passing pirates, it was not a particularly "nice" neighborhood.
Immediately following General Jackson's John Quincy Adams, Secretary of State under President James Monroe, negotiated the Adams-On"s Treaty, which went into effect two years later. While gaining all the Gulf Coast east of New Orleans, the U.S. was obliged to accept a western boundary with New Spain (Mexico) defined by the Sabine, Red, and Arkansas Rivers to the 42nd parallel, thence straight to the Pacific Ocean. (See map, next page.) The Adams-On"s Treaty quashed any American claim to Texas as part of the Louisiana Purchase, but at least the United States was now in control of the entire Gulf Coast east of the Mississippi, including Florida, and its southwestern boundary was firm—for the time being. As a bonus, Spain obligingly surrendered to the U.S. whatever claims to Oregon Territory she had accumulated over the years, leaving the U.S. to work things out on its own with the British up there.
And the price of it all? With the U.S. agreeing to assume outstanding Spanish debts to American citizens who had suffered losses under their regime, which amounted to $5 million, it came to about twelve cents an acre, not counting Oregon.
Altogether, the fortunes of "the Floridas" between 1803 and 1819 were so complex, and often so dramatic, that in terms of daily news-bites the rest of the Louisiana story must have read like backpage boilerplate.
There is a brief but colorful footnote to this era in the history of Louisiana that must not be overlooked. In April of 1804, a month before the Lewis and Clark Expedition set out from Camp Dubois to head across the northwestern part of Louisiana, Jefferson set plans in motion for another expedition into a different region. Precisely two years later, in April of 1806 a party of explorers led by Thomas Freeman and Peter Custis set out from Natchez to explore the Red River. Their objective was to "ground-truth" that part of the boundary between Louisiana and Mexico. They were better prepared, better manned, better funded and better equipped than the Corps of Discovery, but on July 30, only 615 miles up the Red, Spanish soldiers forced them to turn back. Before Lewis and Clark arrived back in St. Louis in September, the Freeman-Custis expedition was finished and forgotten.
For further reading:
For a concise summary of the place and period in question, see Charlton W. Tebeau, A History of Florida (Coral Gables: University of Miami Press, 1971), Chapter 8.