On the 14th of May, 1804, Captains Lewis and Clarke, with forty-two men, under the direction of the War Department of the Government, started from their encampment at the mouth of Wood River, in what is now the State of Illinois, to explore the Missouri River and the unknown regions of the Northwest. After many strange adventures, and the accomplishment of a thousand miles of their journey, on the 18th of August they landed on the Nebraska side of the river, nearly opposite the southwest corner of the present Woodbury, where they held a council with a party of Otoe and Missouri Indian Chiefs. On the morning of the 20th the Indians mounted their horses and left, having received some presents from the whites.
On the 19th, in camp at the place where the council was held, Sergeant Charles Floyd, of the expedition, became very sick and remained so all night. The next morning, however, which was Monday, August 20, the party set out on their journey up the river. Having a “fine wind and fine weather,” they made thirteen miles, and at two o’clock landed for dinner on the Iowa side of the river. Here Sergeant Floyd died. About one mile farther up the river, on the summit of a high bluff, his body was buried with the honors due to a brave soldier. His comrades marked the place with a cedar post, on which were inscribed his name and the date of his death. About one mile above, a small river flows into the Missouri, and here the party encamped for the next day. Captains Lewis and Clarke gave this stream the name of Floyd’s River, to perpetuate the memory of the first man who had fallen in their expedition. The next day they set out early, passed the bluffs, now within the limits of Sioux City, which are mentioned in the journal of Patrick Gass, a member of the expedition, as “handsome, pale colored bluffs.” Willow Creek and Big Sioux River, the latter just above where Sioux City now stands, are also mentioned. During a great freshet in the spring of 1857, the turbulent Missouri washed away a portion of the bluff, so as to expose the remains of Sergeant Floyd. The citizens of Sioux City and vicinity collected the remains and re-interred them some distance back from the river on the same bluff.
The title of the Indians to the land in this portion of Iowa became extinct in 1847, and in the summer of 1848, forty-four years after the burial of Sergeant Floyd, a single pioneer, named William Thompson, settled at Floyd’s Bluff the first white man who became a permanent settler of the county. In the autumn of the same year his brother Charles and another man followed and spent the winter there, being, at that time the only white men in the county. Anticipating an immense immigration, he laid out a town here and named it in honor of himself Thompson town. Like other western towns, this for a while was supposed to be the point. To give it an air of business, and aid in its development, he erected here his cabin, and, on the organization of the county, in 1853, this was made the county seat. It was a sort of post for Indian traders for some years, but the city lots were too steep for cultivation, or for building, and, unfortunately, there was no place for a landing on the bank of the river, and the stakes are all that now remain to mark the progress of the town.
Source: Woodbury County Iowa, History of Western Iowa, 1882