Most, but not all, large size national banknotes showed the charter number of the issuing bank on the obverse. In some cases the charter number was printed once, but typically the charter number appeared twice. The issuing bank's charter number was carefully positioned inside the engraved border, as well as overprinted elsewhere on the obverse. To aid Treasury workers in sorting banknotes, later large size notes also showed a letter to indicate the region of the country in which the issuing bank was located—"N" for New England, "E" for East, "S" for South, "M" for Mid-West, "W" for West, and "P" for Pacific coast.