The U.S. Mint struck only 13 different gold commemorative coin designs in the early part of the last century, all with incredibly tiny mintages. Nine coins are $1.00 denomination, two coins are $2.50 denominations, and two coins are $50.00 denomination.  All were struck at the Philadelphia Mint, except for the 3 Panama-Pacific Exposition issues, which were struck at the San Francisco Mint. All of these gold coins are scarce to rare, yet are surprisingly affordable, given the mintage figures.  Take on the challenge of assembling the entire series!