> You would need to completely remake all bills in circulation with a new style and make invalid the old style... It takes a while for all the old bills to get

> You would need to completely remake all bills in circulation with a new style and make invalid the old style... It takes a while for all the old bills to get out of circulation though -- a few years ago I got my hands on a $20 bill from 1970 and the kid at the corner store almost didn't take it since they had apparently never seen one that old, probably didn't help it was nice and crisp as well. Only thing I can imagine is someone was saving it from their birth year and had to spend it for whatever reason since $20 in 1970 was over $100 in today's dollars so they lost a bunch of value holding that bill.