cash is largely minted by the government, and they usually aim to maintain "enough" (currently 2.3k billion dollars currently?)
Most of the money supply is not in physical cash, though- they call that the m1 supply which is found in things like savings and checking accounts, other kinds of deposit accounts, etc.
Currency is added to the economy by buying back government securities (think bonds). Specifically this is the Federal Reserve. we also pay interest on money held at by the Fed. (Banks invest the money.)


said another way.... they think our food cleanliness is somewhere between "dirty as fuck" and "You eat that?!"