What is the difference between a 1953A and 1953B US 5 dollar bill?

For any US bills issued since 1928, a letter next to the date indicates the part of the printing "series" in which the bill was issued.

Unlike coins, the date on a bill only indicates when its particular series began. For historical reasons the first set of bills in any series doesn't have a letter. When a new set starts, an "A" is added, then "B", and so on. That means your bills were printed respectively in the second and third sets in the 1953 series.

Two different types of 1953 $5 bills were printed: red-seal United States Notes and blue-seal silver certificates. For information about values, please see the Related Questions.

More DetailsBased on the bills' series and type, it's possible to tell very roughly when they were printed. The 1953-A bills were printed some time after July, 1957 and most likely up to early 1961. The 1953-B's were probably printed from early 1961 to early 1962.

The rules that determine dates and letters have changed over the years. Originally a new series date was only started when there was some major change to a bill's design or the printing process. A letter would be added if and when either a new Secretary of the Treasury or US Treasurer was appointed. Because bill designs didn't change very often that practice led to the rather absurd situation of 1935-dated $1 bills being printed well into the 1960s.

Starting in 1974 the Treasury changed the rules to assign a new series date when either a new design was adopted or a new Secretary was appointed. A letter would be added only if a new Treasurer was appointed. Because Treasury Secretaries normally serve only the president who appointed them, the new rules mean that bills' dates change much more often and there are very few different series letters. Check the bills in your wallet to see how it works.