Q:

What states explicitly ban carrying concealed weapons on college campuses?
A:

Six states in the South (Arkansas, Florida, Mississippi, Missouri, North Carolina, and Tennessee) have explicit bans on concealed weapons on college campuses.

(Source: Stateline.org)

Nationwide, 38 states (including 15 of the 16 states in the South; Oklahoma is the lone exception) ban weapons from schools in general.  Of those, 16 states explicitly prohibit carrying concealed weapons on college campuses (6 SLC states, listed above).  The 12 states that do not have weapon bans allow individual schools to decide on such policies (with the exception of Utah, where public universities are prohibited from making concealed-weapon restrictions).  Also, Illinois and Wisconsin are the only two states that do not allow people to carry concealed weapons anywhere, i.e. do not issue concealed weapons permits.