I-70 roughly divides the state north and south. So north of it, it tends to feel more Midwest. Very much like Iowa. But south of it, it definitely starts feeling more Southern.

But both KC and STL are solidly Midwestern. It actually makes more sense to look at them from another dimension: east-west. St. Louis is the western-most "Eastern" city, while Kansas city is the eastern-most "Western" city.