Des Moines Rapids

The Des Moines Rapids between Nauvoo, Illinois and Keokuk, Iowa-Hamilton, Illinois is one of two major rapids on the Mississippi River that limited Steamboat traffic on the river through the early 19th century.

The rapids just above the confluence of the Des Moines River were to contribute to the Honey War in the 1830s between Missouri and Iowa over the Sullivan Line that separates the two states.

Various attempts to make the river navigable started in 1837 when a channel was blasted through the rapids by U.S. Army Corps of Engineers team led by Robert E. Lee.

However, thwarted by its constitution which clearly stated the Des Moines River was the border, it instead asserted that there were no rapids where the Sullivan line crossed the Des Moines and conducted a new survey which said the rapids of the Des Moines were about 9.5 miles (15.3 km) north, near Keosauqua, Iowa, and attempted to collect taxes in the area.

The Supreme Court was to ultimately decide in State of Missouri v. State of Iowa, 48 U.S. 660 (1849), that Iowa's southern boundary was the foot of the rapids at modern day Keokuk (although accepting the Sullivan Line for the rest of the border from about 20 miles (32 km) west).