Cairo, the southernmost city in Illinois, has the lowest elevation of any location in the state at 315 feet above sea level. During the Civil War, Admiral Foote made Cairo the naval station for the Mississippi River Squadron. In 1862, General Grant built Fort Defiance to protect the Confluence of the Mississippi and Ohio Rivers. Following the Great Mississippi Flood of 1927, USACE built the Birds Point-New Madrid Floodway, part of the Mississippi River and Tributaries Project, as a flood risk management measure for Cairo and other communities.
