What does different letters mean on $2 bills mean

What City and State, look real close at the Large A, B, or C, and you will be able to read where from.

Series ABC are production runs. Just like a book has the first edition, 2nd... The first run does not have a series letter; therefore, series A is the second edition. There are letters on older bills that designate which of the 13 Federal Reserve Banks first distributed the bank notes. 'G' is Chicago, IL...

Try this link and scroll down to Federal Reserve District SealIt shows the letters for the States:
Have you ever wondered about a $1 bill?

A=Boston
B=New York
C=Philadelphia