The only San Francisco gold dollar produced after the Civil War was the 1870-S. The reason for its creation is unknown, as gold dollars were not needed in commerce at the time and no other branch mints had resumed production. The reason perhaps may have had something to do with the opening of the second San Francisco Mint building.
Various unique denominations were created at the San Francisco Mint that year including the half dime and three dollar gold piece. Perhaps the gold dollar might have been unique as well, but instead a total of 3,000 pieces were reported to have been struck. A sizable number of these have survived, even in uncirculated condition, making this issue not as scarce as the mintage might suggest. Nonetheless, it is certainly an interesting and historic coin, which came to represent the final branch mint issue for the gold dollar denomination.