The number of banks in the U.S. is a legacy of President Jackson, who campaigned (and won) against rechartering the Second Bank of the United States
https://en.wikipedia.org/wiki/Bank_War
From the founding until President Jackson's administration, debate about the extent of Federal power largely revolved around the legitimacy of a national bank. Long story short, the state sovereignty proponents won. And until very recently that victory stuck, even after the Civil War, the institution of the Federal Reserve, and the expansion of Commerce Clause powers. You didn't see any federally chartered banks until the Federal Credit Union Act of 1934, but there weren't any federally chartered banks which challenged the predominance of state chartered banks until the 1980s.
In general, and until very recently, Congress has abstained from directly regulating the banking industry. AFAIU, banks are subject to Federal law primarily indirectly via regulations promulgated by the Federal Reserve. But the Federal Reserve system is opt-in, and many smaller banks contract with larger banks to leverage the Federal Reserve transactional systems, and are therefore for the most part not subject to those rules.
It's all rather ironic because banking was one of the few areas of national commerce that was clearly contemplated to fall under federal regulatory powers, to some extent, during the time of the Constitution. Though opposed by Jefferson and Madison, the First National Bank was chartered in 1791. Yet now that federal powers have expanded to encompass every aspect of commerce, the legacy of the failure of the Second National Bank remains incredibly strong.
In general, and until very recently, Congress has abstained from directly regulating the banking industry. AFAIU, banks are subject to Federal law primarily indirectly via regulations promulgated by the Federal Reserve. But the Federal Reserve system is opt-in, and many smaller banks contract with larger banks to leverage the Federal Reserve transactional systems, and are therefore for the most part not subject to those rules.
It's all rather ironic because banking was one of the few areas of national commerce that was clearly contemplated to fall under federal regulatory powers, to some extent, during the time of the Constitution. Though opposed by Jefferson and Madison, the First National Bank was chartered in 1791. Yet now that federal powers have expanded to encompass every aspect of commerce, the legacy of the failure of the Second National Bank remains incredibly strong.