there are many different types of notes that were issued.
In the twentith century the history of the depravity of the Marxist Rossevelt cleptocracy was clearly documented by the currency.
Just pick up a book on Paper Money of the United States of America and read through the indroductory chapters. It won't be political but what happened will be obvious.
The Federal Reserve notes USED TO have a gold clause. It was removed.
Then the Gold Certificates went away.
then the National Bank Notes went away with the National Banks. They had 'lawful money' depostied in the Treasury. The Democrats did away with them meanwhile letting the Federal Reserve banksters and their cabal cronies loot all the districts where National Banks had a bank run.
in the 1930s Rosevelt let his bankster pals confiscate as much gold as people were stupid enough to give them. Gold was no longer minted, Gold Certificates were no longer issued.
The Red Seal United States Notes were still issued. This was a kind of money authorized during the Civil War period.
Next the Silver Certificates went away.
Silver coinage went away at the same time.
The Red Seals are still in issue, with a large amount of 100 dollar bills issued in the 1960s (these are very collectible).
Well, so now we have the Federal Reserve Notes.
When the Federal Reserve is reformed or eliminated I expect us to have Silver and Gold notes again, as well as silver and gold coins.
We'll see.