On August 19, 1804, after 98 days of exploring the Missouri River, Floyd became violently ill. L&C described it as bilious colic. A modern review suggests that he suffered from an appendicitis, for which at that time, there was no cure. L&C wrote " S. Floyd as bad as he can be has no pulse & nothing will stay a moment in his stomach or bowls". He could not be saved.
Just before noon on August 20, 1804, the expedition boats pulled up to the east bank of the Missouri near present day Sioux City, IA, and Floyd whispered, "I am going away". He was carried to the highest bluff and buried with full honors of war. The spot was marked with a red cedar post with Floyd's name and date. Sergeant Floyd was the first U.S. soldier to die west of the Mississippi River and would be the only member of the Lewis & Clark Expedition to lose his life.
On their return, two years later, they found the grave disturbed, but intact and refilled it.
The Missouri would erode much of the bluff where Floyd was buried and he was reburied. In 1894, his journal was published and a revival in his grave were undertaken. He was reburied in urns and marked with a large marble slab. Funds were raised and matched by citizens and the state of Iowa to erect a Memorial to Floyd with its cornerstone being laid on August 20, 1900.
Sergeant Floyd was reburied a fourth time, at the core of the Monument which was dedicated on Memorial Day, 1901.
The Sergeant Floyd Monument, a National Historic Landmark, in Sioux City, Iowa, is located along US Hwy. 75, one mile north of 1-29 & US 20 Exit 143. It is open daily, year-round.
(Info taken from NPS information tablet at site)