Banknote serial numbers start with A toL, representing the Federal Reserve Banks.
A also 1 is Boston, L also 12 is San Francisco.
You can look up the others.
The 8 digit number can only go as high as 96,000,000 due to the way sheets of money are printed. The last letter is the printing of each 96000000 starting with A, then to B through Z if that many are printed.