Confluence of the Ohio and Mississippi Rivers

This aerial view shows islands in the Mississippi River constructed from dredged sand by the U.S. Army Corps of Engineers as part of the Upper Mississippi River Restoration Program. These islands help enhance the river’s aquatic ecosystem.

USACE

After traveling more than 900 miles on the Ohio River, Lewis and Clark reached the Mississippi River. On November 14, 1803, they camped at the point where the two rivers joined. They spent several days exploring and surveying the area of the confluence.11

Since their visit, the confluence has shifted southward. Settlement, development, and agriculture have changed the landscape, while engineering projects modified the rivers for navigation, flood control, hydropower, and recreation. In addition to human management of waterways and surrounding lands, climate change played a part in this shift. Extreme weather events, such as the devastating 2011 flooding at Cairo, Illinois, can overwhelm engineering efforts, illustrating how the rivers have become a “complex human-natural system.” Record rains, droughts, and floods inspire an ongoing Upper Mississippi River Restoration Project aimed at making this system more resilient.12

Citations:
11 NPS, “Confluence of the Ohio and Mississippi Rivers,” Pittsburgh to the Pacific: High Potential Historic Sites of the Lewis and Clark National Historical Trail, 2022, 26, https://www.nps.gov/lecl/getinvolved/upload/2022_LCNHT_HPHS_Report_508compliantUPDATE-2.pdf; Joseph A. Mussulman, “The Mouth of the Ohio,” Discover Lewis & Clark, accessed August 26, 2024, https://lewis-clark.org/thetrail/up-the-mississippi/mouth-of-the-ohio/.
12 NPS, “Confluence of the Ohio and Mississippi Rivers,” 26; Kenneth R. Olson and Lois Wright Morton, Management of Mississippi and Ohio River Landscapes, Soil and Water Conservation Society, 1, 6, accessed August 26, 2024, https://www.swcs.org/static/media/cms/Chapter_1_9EFADF945D8F3.pdf; Dea Larsen Converse, “Impacts of Climate Change on the Mississippi River,” Nelson Institute for Environmental Studies, 2021, https://wicci.wisc.edu/2021-assessment-report/water/impacts-of-climate-change-on-the-mississippi-river/; Jason S. Alexander, Richard C. Wilson, and W. Reed Green, “A Brief History and Summary of the Effects of River Engineering and Dams on the Mississippi River System and Delta,” U.S. Geological Survey, 2012, 1, https://pubs.usgs.gov/circ/1375/C1375.pdf.

Climate Change:Lewis and Clark Trail

Lewis and Clark NHT Visitor Centers and Museums

This map shows a range of features associated with the Lewis and Clark National Historic Trail, which commemorates the 1803-1806 Lewis and Clark Expedition. The trail spans a large portion of the North American continent, from the Ohio River in Pittsburgh, Pennsylvania, to the mouth of the Columbia River in Oregon. The trail is comprised of the historic route of the Lewis and Clark Expedition, an auto tour route, high potential historic sites (shown in black), visitor centers (shown in orange), and pivotal places (shown in green). These features can be selected on the map to reveal additional information. Also shown is a base map displaying state boundaries, cities, rivers, and highways. The map conveys how a significant area of the North American continent was traversed by the Lewis and Clark Expedition and indicates the many places where visitors can learn about their journey and experience the landscape through which they traveled.