I’m no economist, however, my guess would be that the $100, because of its denomination size, doesn’t see frequent enough circulation to get it back into the supply. Banks, if I’m not mistaken will retire certain bills and get new ones from the fed. Then the old ones returned to the fed are destroyed. But only banks do this. And since most retailers don’t accept anything larger than a $20 and most large purchases (bills, groceries, etc) are charged to check or plastic, the $100 bill becomes a piece of paper that we have to go to the bank to break into $20’s. The $50 dollar bill is equally as useless since there are plenty of 20’s and 10’s in circulation. $100 bills seem to disappear out of circulation, I suspect, because the end up collecting dust in bank vaults, never seeing an actual register. My question is, why recirculate a pointless bill? For Vegas’s sake?