My Currency Collection Blog

If you look at the star note production tables you'll see sometimes a run labeled 1B or 2B like here. Here's an explanation why these runs aren't labeled numerically as you'd expect.

Some basics of modern star note printing

Star notes are printed in groups of 3,200,000 notes. Run numbers generally align with serial number ranges
Run      Serial Number Range
1 - 0000 0001 - 0320 0000
2 - 0320 0001 - 0640 0000
3 - 0640 0001 - 0960 0000
4 - 0960 0001 - 1280 0000
5 - 1280 0001 - 1600 0000
etc...

After a run of star notes is printed, the next run's starting serial number will jump ahead to the beginning of the next run's range, regardless of how many notes were printed in that run. For example, lets say 1,280,000 notes were printed in run #1 for the Atlanta FRB. The serial number range for these notes is 0000 0001 - 0128 0000. Run #2 printed for Atlanta will start its numbering at 0320 0001. (Serial numbers 0128 0001 - 0320 000 do not exist in this case) This is how printing works normally. This will not create instances of run 1B, 1C, or the like.

Multiple printings per run

Here's a different example: Lets say 640,000 notes were printed in run #1 for the Chicago FRB. The serial number range for these notes is 0000 0001 - 0064 0000. Then, the BEP decides to do a separate printing of 640,000 notes between serial numbers 0064 0001 and 0128 0000. This separate printing is indicated as Run 1B. It's not run 2 because the serial number doesn't fall into that serial number range. It's also cannot be called run 1 because there already exists a distinct printing in the run range.

In summary, when there are multiple distinct printings within a run range, the printings get the A, B, C, or whatever letter suffix.

Why?

What makes the BEP decide to start some printings at the proper run starts sometimes and other times butted right up after the previous printing? There's no rhyme or reason as far as I can tell.