Although they are still technically legal tender in the United States, high-denomination bills were last printed on December 27, 1945, and officially discontinued on July 14, 1969, by the Federal Reserve System, supposedly due to 'lack of use'. The $5,000 and $10,000 effectively disappeared well before then.
The Federal Reserve began taking high-denomination currency out of circulation (destroying large bills received by banks) in 1969. As of May 30, 2009, only 336 $10,000 bills were known to exist; 342 remaining $5,000 bills; and 165,372 remaining $1,000 bills.[10] Due to their rarity, collectors often pay considerably more than the face value of the bills to acquire them. Some are in museums in other parts of the world.