The Federal Reserve
The Fed is the country's central bank. The Federal Reserve controls how much, and what money is in circulation. They distribute the money to member banks. When the banks don't need any more money, they send it back.
The Federal reserve distributes money to the 12-district banks...
... which is run by the Board of Governors! And Distributes the money to banks all over!
What about the FOMC (Federal Open Market Comitee)? They are The Fed's chief body for monetary policy.
Or the US Mint? They make all the "fancy stuff"; like US Mints, Medals, foreign currency, etc.
Woah woah woah.. well how is all this money made?
The Department of Engraving & Printing creates the paper money, and works out all the securities for The Fed.