From Wiki of The Public Library of Cincinnati and Hamilton County
The Ohio River flows through or borders six states: Illinois, Indiana, Kentucky, Ohio, Pennsylvania and West Virginia. It is 981 miles long, starting at the confluence of the Allegheny and the Monongahela Rivers in Pittsburgh, Pennsylvania, and ending in Cairo, Illinois, where it flows into the Mississippi River. The Mississippi River is one of the world’s major river systems in size, habitat diversity and biological productivity. It ranks fourth behind the Nile, Amazon and Yangtze rivers. It is more than 2,300 miles long and 11 miles across at its widest parts. Even though early pilots kept detailed maps and charts, the course of a river was subject to change. There were many perils to navigation including ice, obstructions, low water levels, floods, falls, rapids, fires, boiler explosions and pirates. This collection presents some of the tools that made navigation of the Ohio and Mississippi Rivers possible, and the historical records that resulted.