Here are the rules of regionalization, per the NCAA (I've bolded the key notes to remember that are relevant to Central Region teams):
-Regions will be determined by state boundaries.
-A state may reside in more than one region.
-All opponents within your geographic region are in-region contests.
-Conferences will be assigned to specific regions for automatic qualification and post-season competition.
-Conference opponents will count as in-region contest regardless of geographic location.
-Opponents residing within your state regardless of conference affiliation are in-region contests.
-All opponents (regardless of conference affiliation) in states contiguous to your state are in-region contests.

The committee has approved the following principles and any changes or additions to these principles must beapproved by the committee.
-Institutions in the state of Montana will be able to consider Nebraska and Colorado as contiguous states (and viceversa). (There are no Division II institutions currently in state contiguous to Montana’s southern border.)
-The west region may consider the states of North Dakota, South Dakota, Nebraska, Colorado and New Mexico ascontiguous states (and vice versa).
-Institutions located in MINNESOTA and MICHIGAN may compete against each other and be considered ascontiguous states (those contests count as in-region).
-Institutions located in Colorado and Texas are considered contiguous and may count competitions between theseinstitutions as in-region contests.
-Institutions located in Texas and Mississippi are considered contiguous and may count competitions between theseinstitutions as in-region contests.
-Institutions and conferences with a common mission (i.e. Historically Black Colleges and Universities) mayconsider inter-conference contests or independent contests against schools with similar missions as in-region,regardless of their geographic location and/or regional assignment.
-Institutions in the Atlantic and East Regions will be able to consider the District of Columbia as in-region contests.