American dollar coins have been minted intermittently since 1794, currently there are
three dollar coin series in production:
The Presidential $1 Coin Series (begun in 2007), the
Sacagawea Golden Dollar (first issued in 2000), and the
Native American $1 Coins(first issued in 2009).
All three dollar coins are golden in color, created by a mixture of metals (none of them gold). These dollar coins have the same "electromagnetic signature" as their predecessor, the Susan B. Anthony (SBA) dollar, which was silver in color. Keeping this signature allows older vending machines to accept the new coins without being retrofitted.
