From the New York Times, October 19, 2015:
. . . “California is the only state that I know of that has passed a modern ban on people being able to carry a gun on college campuses,” said John Lott, the head of the Crime Prevention Research Center, who testified last week in favor of the Michigan bill to permit concealed guns on campus. “The California law is interesting in that, can you point to one example of any problem they’ve had with the current rules? So why are they changing it?”
Since 2007, Idaho, Kansas, Mississippi and Wisconsin, as well as Texas, have passed laws that allow or will allow licensed gun owners to carry firearms on campus. Courts in Colorado and Oregon affirmed the right to carry guns on campus.
“Over the past three years, we have seen 12 to 20 states introduce legislation every session to allow guns on campus,” said Suzanne Hultin of the National Conference of State Legislatures. “And every year, one or two states enact that legislation.”