BEP Production Reports: These are monthly reports issued by the Bureau of Engraving and Printing (BEP), almost like detailed receipts.
They detail the very number of notes printed for every series, denomination, and FRB district. They even account for specific start and end serial numbers for every print run.
USPaperMoney.io: This incredibly in-depth online resource delves into all things modern US currency.
It offers a lot of information such as serial number ranges, the persons who signed various note series, and even finer design elements.
