It's inside the Federal Reserve Seal, located on the left side of the bill's front, very much like the seal on a $1 bill. The issuing district is shown in small type surrounding the large district ID letter.
The term "issuing district" does NOT mean where the bill was printed, simply which Federal Reserve District requested and distributed it. All 1976 $2 bills (in fact, all US bills up till 1991) were printed at the Bureau of Engraving and Printing in Washington.
The large letter in the center of the deal indicates the Federal Reserve District.
There were no series letters on any 1929 US bills. You may be referring instead to the Federal Reserve District letter; "G" indicates your bill was distributed by the Chicago district. There's more information at the question "What is the value of a 1929 US 100 dollar Federal Reserve Note?"
"A" is the highest series letter for 1928 $50 Federal Reserve Notes. "K" is most likely the Federal Reserve District letter. The series letter, if any, on US bills is next to the date. Please see the question "What is the value of a 1928 US 50 dollar Federal Reserve Note?" for more information on values.
Bills from the Kansas City Federal Reserve Bank will have the letter J and the number 10 on them.
There were no series letters on any 1929 US bills. You may be referring instead to the Federal Reserve District letter; "G" indicates your bill was distributed by the Chicago district. There's more information at the question "What is the value of a 1929 US 100 dollar Federal Reserve Note?"
"D" is the highest series letter for a 1934 $10 FRN. The series letter is next to the date. A "J" would most likely be a Federal Reserve District letter. Please see the Related Question for more information.
It depends on what letter, if any, is next to the date. A 1928 C bill from the Cleveland* Federal Reserve District is quite valuable, with prices for a circulated bill in the $250 to $450 range as of 10/2011. Other letters are much more common; please see the Related Question for more. (*) To explain, there's no "Federal Reserve of Ohio". It's actually the Fourth Federal Reserve District which has its offices in Cleveland, so it's generally referred to as the Cleveland Federal Reserve District.
The 1934 series only extends to the letter D. You may be confusing the series letter with Federal Reserve Bank letter, which is "E" for the Richmond Federal Reserve District.There's more information at the Related Question.Note that the bill was actually printed in Washington; the Richmond district ordered it and distributed it.
The "4-D" indicates you have an early Federal Reserve Note; those are the code number and letter for the Cleveland OH district. There's more information at the question "What is the value of a 1914 US 5 dollar Federal Reserve Note?".
Modern US $1 and $2 bills still carry the old-style Federal Reserve seal that includes the district letter and name. It's the large circle on the left side of the bill's front.However older $1 bills (before 1963) and $2 bills (before 1976) weren't issued by the Federal Reserve System so they don't have any seal or district identifiers.
The Federal Reserve District letter identifies which of the 12 districts distributed the bill. Many people assume that the bills are actually printed in that district, but in fact all US bills are printed at facilities of the Bureau of Engraving and Printing in either Washington or Fort Worth. The BEP takes orders from each Federal Reserve district, prints bills with that district's seal, and sends them back to the district's central banking repository for distribution through commercial banks. The district letter is shown inside the seal on $1 and $2 bills. Higher-denomination bills no longer have the district letter in the seal, but instead it's incorporated as part of the bill's serial number.
One-dollar and two-dollar bills have city names around the Federal Reserve seal on the left-hand side of the bill. The letter in Federal Reserve Seal is a reference to the city where the Federal Reserve Bank that distributed them is located. For example, C means it was distributed by the Philadelphia bank, K means Dallas, etc.Higher-denomination bills use a "generic" Federal Reserve seal; the corresponding letter appears as part of the bill's serial number instead.Many people believe that bills are actually printed in each district, but in fact they're all printed at plants operated by the Bureau of Engraving and Printing in Washington and Fort Worth. When a district bank determines more bills are needed, they're printed for the requesting district with the appropriate seals and/or letters, then shipped to the district for distribution.