State size comparison
Illinois is about 1.2 times smaller than Missouri.
Missouri is approximately 178,414 sq km, while Illinois is approximately 143,961 sq km, making Illinois 80.69% the size of Missouri. Meanwhile, the population of Missouri is ~6.0 million people (6.8 million more people live in Illinois).
This to-scale comparison of Missouri vs. Illinois uses the Mercator projection, which distorts the size of regions near the poles. Learn more. Note: Try dragging the outline to reposition.