I'm guessing it's that the US Currency was backed by gold and later silver and the central banks couldn't print currency without some precious metal to back it up.
It's the other way around. US switched from a bimetallic system to the gold standard in 1873.
> I'm guessing it's that the US Currency was backed by gold
Well sort of, only until 1971 (or to some extent 1933) though. So you maybe could do that if you wanted to compare the price of housing in the 1870s and 1920s, certainly not between 1970 and the 2020s.
