The Grand Excursion into the Southwest launched to some fanfare from Natchez, Mississippi, in April of 1806. That required taking these two specially constructed flatboats, these experimental craft, down the Mississippi River about fifty miles, and then into the mouth of the Red River, and turning, then, up the Red River to an exploration the Jefferson administration assumed would be probably thirteen hundred miles, all the way to the mountains near Santa Fe.
At the last minute, just before the expedition left, Jefferson and Dunbar decided to limit the expedition to an exploration of the Red River alone. Part of this had to do with Dunbar's experiences with portages in that Washita River expedition of a year and a half earlier, and so he basically talked Jefferson into limiting the expedition to one river. Dunbar really wanted to explore the Arkansas River because he was afraid that Spaniards would stop the party on the Red. But Jefferson insisted on the Red River, and so this is the river that the party turned into, then, on May the first of 1806, with the idea of penetrating it some thirteen hundred miles to its headwaters.
Jefferson was interested in the idea of opening up Santa Fe to American commercial development, and he also had the sense that major rivers come out of mountain ranges. He had been given information from General Wilkinson in 1805, in fact, that seems to have come from early American traders that had penetrated into the southwest, that the Red River did, in fact, drain a mountain range. Wilkinson had told Jefferson, by letter, that far upriver the Red River forked. The north fork, Wilkinson said, flows through a range of mountains, and it's the same mountain range that the Arkansas River heads in. Jefferson assumed, of course, that this was the Rocky Mountains.
In fact, what Wilkinson was describing, from these early trader accounts, was that the north fork of the Red River, which actually flows through the Wichita Mountains of present-day western Oklahoma. The Arkansas River doesnÕt head in the Wichita Mountains, it heads in the Rocky Mountains about three hundred and fifty miles farther to the northwest. Wilkinson also said that the main fork of the Red River headed on the east side of a height, the top of which presented an open plain. And he said, that height requires the Indians three to four days to cross. It is almost entirely destitute of water, and when you get to the other side of that immense open plain, that elevated plain, there are waters flowing southward that are presumed to be waters of the Rio Bravo, or the Rio Grande. And he said, to the northwest a line of mountains running north and south can be seen.
Now what Wilkinson's informants were telling him about was the actual true source of the Red River, which in fact does not drain from the southern Rockies at all, but has its sources in the Llano Estacado, an immense plateau out on the plains of Texas and New Mexico. The headwaters of the Red River is considered to lie today in Palo Duro Canyon, a bright, multi-hued, beautiful desert canyon, that's kind of a small-scale twin of the Grand Canyon, in what is now the Texas Panhandle.
Jefferson, however, seems to have persisted in his belief, despite this, what he must have thought was confusing evidence, that the Red River came out of the southern Rockies near Santa Fe, and so he sent his expedition, then, in May of 1806, up the Red, with the expectation that his explorers were going to reach the Santa Fe area. That was not, however, to be.
Among the array of scientific discoveries that the Jefferson expedition into the southwest hoped to make, were not only masses of metal (that turned out to be meteorites), mountains of partial salt—and that, in a way, reflected reality because the Red River did, in truth, head in an area that is laced with gypsum; it's an extremely salt-laden region and so that was not entirely a chimera. But one of the other things that really intrigues Jefferson about the southwest were reports that wild horses roamed the southwest in large herds. In fact, some of his informants told him that there were herds of thousands of wild horses in the southwest. And this really intrigues Jefferson because he said, If true, this is the first time in the modern age that the horse can be studied in its wild state. So he was very interested in having his explorers have a look at these herds of wild horses. Unfortunately, they never do make it far enough west to see those large herds. But this was another reality; the southwest was full of—some estimates are—as many as two million wild horses in 1800.