Iowa is north of Missouri.
There are three: South Dakota, Iowa, and Missouri, with the Missouri River forming all of the border with Iowa.
The most southern state Iowa borders is Missouri. However, Missouri is a Midwestern state and not a Southern one.
Lots of states are west of Illinois; the two immediately bordering it on the west are Iowa and Missouri.
Missouri and Iowa share a border. You can literally stand with one foot in Missouri and one foot in Iowa. Now if you want to re-ask the question with the names of a Missouri town and an Iowa town you are interested in, a definite answer could be given.
Iowa borders the entire northern edge of Missouri.
Missouri.
Wisconsin, Indiana, Kentucky, Missouri, Iowa
The state above Missouri is Iowa.
Missouri, Iowa, Indiana, Wisconsin, Kentucky
Iowa's southern border is with the state of Missouri.
Iowa borders Missouri to the south.