The capital letter beginning the serial number, which is also shown in a little seal, used to fascinate me as a child. You could tell which Federal Reserve Bank had printed the note - where it had come from. A was Boston, by far the most numerous; B New York, C Philadelphia, etc. We seldom saw anything else up here in NH. To see a J, Kansas City, or an L, San Francisco, was a rarity. Money didn't move about the country as much as it does now. I didn't have an internet to look up the information on then, so I wondered where I or K came from. Someone at a bank or a coin shop could probably have told me, but I wanted to discover them on my own. I didn't know E was Richmond until I went to college in Williamsburg. I didn't know K was Dallas until just now.
How had the bill migrated this far, I wondered. What wild chain of events could have moved money from Minneapolis to here? Such things are unremarkable now. I have no interest in "Where's George," following the current travels of a bill, because the many possibilities are too easy to see now. In 1964, a bill coming from Atlanta, Georgia might as well have come from Tbilisi, Georgia.
Did the five-dollar bill have the same letter codes? Probably, but fives were as rare as bills with a G then. I first carried a twenty of my own in 1970 (two, actually), to pick up my tux for the Junior Prom.