The federal government is the worst 'wildcat' bank as it's a wildcat bank who has refused to redeem dollars for the gold they said it was backed by (eventually in '71 totally reneging their obligation), at one point even outlawing private ownership of gold (the item the currency was backed by) and actually intentionally destroy the currency by target of at least 2% each year. A wildcat bank whos notes you are compelled to purchase, at pain of being in violation of tax law.

At least in the old wildcat banks, you had a shot of redeeming for specie if you went out to the sticks where the main branch was.