We know that since it's inception in 1986, the American Silver Eagle bullion has been minted in the West Point mint. But it was recently uncovered by NGC that the other mints; San Francisco and Philadelphia mints have shared the production of the Silver Eagle bullion coins owing to huge demand for them. Around 79,640 were minted in the Philadelphia mint in 2015 and they are quite hot. Read more about them here. Each of the mints have a specific function that we should know before understanding how the 2017 American Eagle bullion coins are different.
Philadelphia Mint, the first established mint of the United States, started off as the gold and silver repository and mint all combined into one. Till 1833, this small mint (by today's standards) provided currency for the entire nation. The mint location in Philadelphia was changed twice after that and the current mint building was established in 1969. The mint produces circulating coins, numismatic products like the annual coin sets, commemorative coins, medals and the dies for making the coins and medals.
San Francisco Mint
The San Francisco Mint was established in 1854 to mint the gold that was being mined in the California Gold rush. The mint braved an earthquake and fire to be called the 'Granite lady' and later became a National historic landmark. The new mint was established in 1937 and produces Clad and Silver Proofs/Proof sets and other Commemorative coins.
West Point Mint
The West Point Mint was first established in 1938 as a Bullion repository. The facility helped to store Silver and had a capacity of 2 billion ounces, equivalent to 70,000 tonnes of Silver. In later years, the facility started producing coins in order to take off the pressure from other mints because of the huge demand. In 1988, West Point facility got the official status of a U.S. mint. Till now, the mint has produced the bulk of the bullion coins for the U.S. population. Or so we thought!
2017 American Silver Eagle
When NGC along with Coin World, filed a Freedom of Information Act (FOIA) request to the U.S. mint on the mintage of Silver Eagles and mint location, the reply was astounding! The U.S. mint confirmed that the Philadelphia mint produced 1,000,000 and the San Francisco mint some 3,000,000 Silver Eagle bullion coins this year while it was always thought that only the West Point mint produced bullion coins. As mint marks are not added to bullion coins, the only way to find if you have a Philadelphia or a San Francisco Silver Eagle is through the serial numbers; 6 digits starting with 5 for Philadelphia and 6 digits starting with 4 for San Francisco, while West Point serial numbers start with 1,2, or 3.