Question: is it illegal to carry a knife in usa

Answer: Yes, Under the Switchblade Knife Act of 1958 (amended 1986, codified at 15 U.S.C. §§1241--1245), switchblades and ballistic knives are banned from interstate shipment, sale, or importation, or possession within the following: any territory or possession of the United States, i.e. land belonging to the U.S. federal government; Indian lands (as defined in section 1151 of title 18); and areas within the maritime or territorial jurisdiction of the federal government, with the exception of federal, state law enforcement agencies and the military. In addition, federal laws may prohibit the possession or carrying of any knife on certain federal properties such as courthouses or military installations. U.S. federal laws on switchblades do not apply to the possession or sale of switchblade knives within a state's boundaries; the latter is regulated by the laws of that particular state, if any.