Oklahoma part of the South? BWAHAHAHAHAHAHAHAHA! You've obviously never been here. Tulsa has WAY more in common with Kansas City than Atlanta, Little Rock, or Memphis.
Kansas City is a border area between part of the Plains (eastern CO, KS, NE), the Midwest (IA, IL), and differing areas of the South (OK/TX vs. AR/LA/MS). Missouri is an interesting state being as it has a foot in both the Midwest (IA, N 2/3rds IL, IN, OH, WI, MN, MI) and the mid-South (AR, KY, TN).