How can you tell what series a us dollar bill is?

Answer 1

The series is simply the date. Sometimes people include the letter, if any, next to the date when describing the series.

Dates on US bills don't refer to when the bill was printed, but instead indicate what Treasury Secretary, US Treasurer, and/or design were present when the particular group of bills was first printed. That's the reason for the term "series".

Over the years the Treasury has changed the rules that determine a series - and sometimes even ignored its own standards. In the early 20th century a new series was usually started only when there was a significant design change, such as the new design for $1 silver certificates introduced in 1935.

The first bills in any series are usually but not always printed without a letter next to the date. The second set printed would have an "A", "B" would be on the third, and so on.

In the past a letter was added each time a new Treasury Secretary or US Treasurer took office so if the design didn't change the letters could go quite high. Those 1935 $1 SC's were issued all the way up to H.

In 1974 the rule was changed to be that a new series would start whenever a new Treasury Secretary takes office and a letter would be added only if there's a change in the Treasurer's position. As a result modern bills have much more frequent date changes and series letters haven't gone above B in most cases.

That rule has led to some anomalies too, though. For example a new 2004 series was started when the multicolor $20s were introduced, but by the time the new tens were ready there had been a change in Treasurers. The first "colorized" tens were printed as 2004-A instead of 2004. Somewhat strangely the Treasury didn't start a new series when the new purple and gray five was introduced so both the new and old designs were printed as Series 2006 bills.

Answer 2

The series is the date?