The question of the boundary of the Louisiana Purchase of course was a critical issue to any exploration, either into the northern reaches or the southern reaches of the Purchase. And I think the boundary question on the south was especially vexing for Jefferson's administration, in part because Louisiana was purchased from a French government that had not actually taken possession of Louisiana from Spain, and a French government that hadn't actually owned Louisiana in something like thirty-five years. Napoleon's...what he called a retrocession of Louisiana to France in 1800 only lasted for three years. And it was such a brief time that France never sent any of its officials to Louisiana in order to take over the management and control of that province.
And so in order to determine the boundary between Spanish and American possessions, both American investigators and Spanish investigators had to look back thirty-five or forty years to try to determine what the boundary had been between France and Spain in the Louisiana Purchase Texas area back when both those powers had been on the continent.
In fact, there was even a major work published out of all this, by a Spanish priest called Father Pichardo, that attempted to refute the American claim as to where the boundary was. The reason Picardo felt like he had to refute the American claim was because Jefferson, doing research in his own library, concluded that the actual boundary of the Louisiana Purchase on its southwestern side was the Rio Grande River, which meant that all of Texas and half of New Mexico would actually end up belonging to the United States.
Spain of course, was not by any means willing to honor that sort of claim. I think you'd have to say that it was kind of a spurious claim at best. It was based on a very short-lived French colony in the 1680s. So Spain basically asserted that the boundary of the Louisiana Purchase extended from the Sabine River northward to the Missouri River. Spain essentially outdid Jefferson in asserting a grandiose claim to the West.
And so that meant that, in essence, the entire country between the Missouri River and the Rio Grande was up for grabs. It was up for some sort of resolution. And I think one of the reasons the Red River of the South became the place where Jefferson decided to send an expedition was because it would serve as a suitable compromise boundary between the Rio Grande and the Missouri.