Most states require a permit, testing, et cetera for carrying a concealed weapon/gun. In fact, there is only one state that doesn't require a permit.

FWIW, the Sikh religion requires that their men carry a kirpan, to be used only for defending oneself, or defending those who cannot defend themselves. There were incidents involving Sikhs and their kirpan after Sept. 11. I've not heard of any recently.