Lowest and Highest Points in Illinois
Low elevation: <290 feet above mean sea level
Place: Mississippi and Ohio Rivers
7.5' quadrangle name: Wyatt
PLSS: 3-32-17S-1E
Geology: Cahokia Alluvium in river valley
High elevation: 1235 feet above mean sea level
Place: Charles Mound
7.5' quadrangle name: Shullsburg
PLSS: 4-13-29N-2E
Geology: Silurian limestone hill
Area: 55,768.37 square miles
Total relief (approximate): 945 feet
Average percent slope: 1.15%
Updated 10/1/2009 JKH