Why did they put the presidents' faces on US coins?
The first "presidential" coin was the Lincoln cent. Lincoln's
image was put on the coin in honor of his centennial anniversary.
For a long time after that it was considered to be a kind of
one-time decision, but in 1932 the Mint used similar thinking to
issue a commemorative quarter in honor of George Washington's
bicentennial anniversary. The coin was only supposed to be issued
for one year but was so popular that the design was brought back in
1934 and we still have it today.
Those 2 decisions set the precedent for the use of presidential
portraits in spite of George Washington's original insistence that
coins should never carry portraits; he felt that it was similar to
the practice of putting the King's image on a coin like they did in
England.
Jefferson's image followed in 1938, because he is considered
almost as important as Washington in founding the country. FDR's
image went on the dime in 1946 because he had polio and was a
founder of the March of Dimes to collect money for research.
When the Walking Liberty design expired in 1947 Ben Franklin was
chosen as the first non-president, but that design lasted only
until the Kennedy assassination. Originally the plans were to put
his portrait on the quarter but it was felt it would be
inappropriate to displace Washington, so the half was chosen
instead as it was now the only coin not to have a president's
image. Unfortunately the result was that the new halves were saved
by the billions as mementos, effectively killing the denomination
as a circulating coin.
Presidential portraits have now become so much a part of coinage
that they are fiercely defended by the delegations from each
leader's state, often for purely political purposes. For example
when the Mint proposed removing Jefferson's portrait from the
nickel, the VA delegation used parliamentary maneuvers to hold up
almost all work in Congress until a bill was passed guaranteeing
that TJ's picture would stay on the coin forever. Given that
action, it's very unlikely that our coins will ever have any other
images on them, sad to say.