Yep, Missouri treats 'contiguous states' similar to an in-state status, or at least it used to be. They recently updated the website and it seems less preferred than it did last year. They used to say if you had at least a 28 MCAT and 3.5 gpa from a contiguous state you would automatically be given a secondary, similar to an in-state resident. That seems to be a bit different this year:
"The University of Missouri School of Medicine is a state-supported public institution. Because of our responsibilities to the citizens of Missouri, overwhelming preference is given to those applications for admission submitted by legal residents of the state.
Residents of geographically-contiguous states (Kansas, Nebraska, Iowa, Illinois, Kentucky, Tennessee, Arkansas and Oklahoma) are encouraged to submit applications if they have particularly strong credentials.
Individuals residing in all other states are eligible for admission, but their applications are unlikely to be successful unless the admissions committee finds some compelling reason to make an exception. Examples of such compelling reasons include exceptionally strong academic credentials, strong ties to the state of Missouri, and/or personal characteristics, backgrounds and experiences adding uncommon and desirable diversity to an entering class. Applicants must be either US citizen or permanent resident."
http://medicine.missouri.edu/admissions/outofstate.php