With this agreement, the first phase of the ongoing border dispute between the two nations in this region, commonly called the West Florida Controversy, came to a close.

[1][page needed] Thomas Pinckney negotiated the treaty for the United States and Don Manuel de Godoy represented Spain.

[citation needed] In 1763, West Florida's northern border was initially set at the 31st parallel north, but it was moved in 1764 to 32° 28′, the junction of the Mississippi River and the Yazoo River and now the location of Vicksburg, Mississippi, to give the West Floridians more territory, including the Natchez District and the Tombigbee District.

After reacquiring the colony, Spain insisted that its West Florida claim extended fully to 32° 28′, but the U.S. asserted that the land between 31° and 32° 28′ had always been British territory and so rightfully belonged to the United States.

Grant (1997) argues that the treaty was critical for the emergence of American expansionism, later known as "Manifest destiny," because control of the Natchez and Tombigbee districts was needed for dominance of the Southwest by the United States.

[5] Under the secret Third Treaty of San Ildefonso of October 1, 1800, Spanish Louisiana, comprising both the vast territory west of the Mississippi and New Orleans, was formally retroceded to France, but Spain continued to administer it.

As a result, when France and the United States concluded the Louisiana Purchase in 1803, a new dispute, the second phase of the West Florida Controversy, arose.

This time, the disagreement was over whether the portion of West Florida that was first under British and then Spanish control since 1763 (between the Mississippi and Perdido Rivers) was included in the 1801 treaty and thus the Louisiana Purchase.

"[11] Also in 1812, the U.S. annexed the Mobile District of West Florida between the Perdido and Pearl Rivers and declared that it had been included in the Louisiana Purchase.

The following year, a federal statute was secretly enacted authorizing the president to take full possession of the area with the use of military force as deemed necessary.