The printed design has remained the same but the form factor has been pretty static for the last century or so. Things like bill readers are a big reason for that once they appeared it became a lot harder to swap around bill shapes.
I remember hearing that the Susan B Anthony dollar coin failed because there was no extra position in the coin drawer of cash registers to put it in. Can you image if every cash drawer now has to be redesigned to have different sized bills?
(I know, I know, it's not actually that big a deal. The drawers have removable inserts, but you get the point of it.)
(actually, on second though, automatic bill readers in vending machines, etc. would need a big retrofitting, that's probably much more a big deal).
The cash register issue I think could be papered over by just having the bills be smaller than the existing bills, ie $100s stay the same size and we cut off a bit of the bill for each denomination step downwards. That would keep them fitting in the drawer and be in line with the pattern of other countries who also make larger denominations physically larger.
1971 wasn't such a big deal. Between the 1930s and 1971 only foreign central banks could redeem their dollars in gold. So I would put the 'partial default' in 1933, if you care about gold.
But they had suspended convertibility of dollars into gold every so often before that. (And, of course, the dollar wasn't always about gold. They also experimented with silver and bimetalism.)
> But they had suspended convertibility of dollars into gold every so often before that.
They suspended redemptions of the certificated amount. You could not own gold until 1933 from 1974, but excluding of that, you can always convert your money into gold outside of the government if you want.
