What is the value of a 1928 US 2 dollar bill with a D mint mark?

To explain the letters on bills, "D" isn't a mint mark. The US Mint only makes coins; all 1928 bills were printed by the Bureau of Engraving and Printing in Washington.

A small "D" below the date indicates that the bill was printed as part of the 5th set of 1928-series bills, which in this case refers to the administration of Secretary of the Treasury Henry Morgenthau, Jr. and US Treasurer W. A. Julian.

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