We gotta find a use for $1 billion in unused dollar coins somehow:
In 2005, Congress decided that a new series of dollar coins should be minted to engage the public. These coins would bear the likeness of every former president, starting with George Washington. There would be a new one every quarter. So, far, the Mint has produced coins through the 18th president, Ulysses S. Grant. Members of Congress reasoned that a coin series that changed frequently and had educational appeal would make dollar coins more popular. The idea came from the successful program that put each of the 50 states on the backs of quarters. But as the new presidential dollar coins rolled out, the greenback lost none of its dominance in Americans' hearts and wallets.