In Missouri, it's a Concealed Carry Permit, the possession of which exempts one from several statute subsections:
4. Subdivisions (1), (8), and (10) of subsection 1 of this section shall not apply to any person who has a valid concealed carry permit issued pursuant to sections 571.101 to 571.121, a valid concealed carry endorsement issued before August 28, 2013, or a valid permit or endorsement to carry concealed firearms issued by another state or political subdivision of another state.
(1) Carries concealed upon or about his or her person a knife, a firearm, a blackjack or any other weapon readily capable of lethal use; or
(8) Carries a firearm or any other weapon readily capable of lethal use into any church or place where people have assembled for worship, or into any election precinct on any election day, or into any building owned or occupied by any agency of the federal government, state government, or political subdivision thereof; or
(10) Carries a firearm, whether loaded or unloaded, or any other weapon readily capable of lethal use into any school, onto any school bus, or onto the premises of any function or activity sponsored or sanctioned by school officials or the district school board; or