On July 27, 1804, Lewis and Clark's Corps of Discovery left their "White Catfish" camp and proceeded up the Missouri River. After traveling some distance, Clark "took one man R. Field and walked on Shore with a View of Examoning Som mounds" on the Nebraska side. He found the mounds "of Deffirent hight Shape & Size, Som Composed of Sand Some earth & sand....all of which covered about 200 acres." The mounds may have been the remains of earthlodges, which served as dwellings for Oto Indians who had formerly lived nearby, or they may have been natural. Most were located between what in now Farnam, Davenport, Eight, and Eleventh streets of downtown Omaha. Clark and Field did not reach the evening campsite, near present day Eppley Airfield, until after dark.
The next morning the expedition proceeded on. On August 3 Lewis and Clark met with Oto and Missouria Indians at a place the captains named "Council Bluff," near present day Fort Calhoun, Nebraska. It later became the site of Fort Atkinson.