In the United States, a national bank is an ordinary private bank operating within the federal government's regulatory structure, which usually but not always operates nationally,[1] and is under the supervision of the Office of the Comptroller of the Currency.[2] It is legally required to be a member of the Federal Reserve System.[3] A national bank in the U.S. is distinguished from a state bank, whose permit is granted by one of the U.S. states,[1] and can only do business in that state.[2]