Disputes
Under the secret Third Treaty of San Ildefonso of October 1, 1800, Louisiana and an undefined portion of West Florida were formally transferred back to France, although the Spanish continued to administer it. The terms of the treaty did not specify the boundaries of the territory being returned. When France then sold the Louisiana Territory to the US in 1803, a dispute arose again between Spain and the US on which parts of West Florida exactly had Spain ceded to France, which would in turn decide which parts of West Florida were now US property versus Spanish property.
Read more about this topic: Pinckney's Treaty