History
The Mint's largest facility is the Philadelphia Mint, one of four active coin-producing mints. The current facility at Philadelphia, which opened in 1969, is the fourth Philadelphia Mint. The first was built in 1792, when Philadelphia was still the U.S. capital, and began operation in 1793. Until 1980, coins minted at Philadelphia bore no mint mark, with the exceptions of the Susan B. Anthony dollar and the wartime Jefferson nickel. In 1980, the P mint mark was added to all U.S. coinage except the cent. Until 1968, the Philadelphia Mint was responsible for nearly all official proof coinage. Philadelphia is also the site of master die production for U.S. coinage, and the engraving and design departments of the Mint are also located there.
The Denver branch began life in 1863 as the local assay office, just five years after gold was discovered in the area. By the turn of the century, the office was bringing in over $5 million in annual gold and silver deposits, and in 1906, the Mint opened its new Denver branch. Denver uses a D mint mark, and strikes coinage only for circulation. It also produces its own working dies ,as well as working dies for the other Mints.
The San Francisco branch, opened in 1854 to serve the goldfields of the California Gold Rush, uses an S mint mark. It quickly outgrew its first building and moved into a new facility in 1874. This building, one of the few that survived the great earthquake of 1906, served until 1937, when the present facility was opened. It was closed in 1955, then reopened a decade later during the coin shortage of the mid-60s. In 1968, it took over most proof-coinage production from Philadelphia, and since 1975, it has been used solely for proof coinage, with the exception of the Anthony dollar and a portion of the mintage of cents in the early 1980s. (These cents are indistinguishable from those minted at Philadelphia.)
The West Point branch is the newest branch mint. Its predecessor, the West Point Bullion Depository, was opened in 1937, and cents were produced there from 1973 to 1986. The West Point Mint gained official status as a branch mint on March 31, 1988. Along with the cents already mentioned, which were identical to those produced at Philadelphia, West Point has struck a great deal of commemorative and proof coinage bearing the W mint mark. In 1996, West Point produced clad dimes, but for collectors, not for circulation. The West Point facility is still used for storage of part of the United States' gold bullion reserves, and West Point is now the United States' only production facility for gold, silver and platinum American Eagle coins.
While not a coin production facility, the U.S. Bullion Depository at Fort Knox, Kentucky is another facility of the Mint. Its primary purpose is for storage of the United States' (and other countries') gold bullion reserves.
The Mint manages extensive commercial marketing programs. The product line includes special coin sets for collectors, national medals, American Eagle gold, silver and platinum bullion coins, and commemorative coins marking national events such as the Bicentennial of the Constitution. The Mint's functions include:
Note that the Mint is not responsible for the production of paper money; that is the responsibility of the Bureau of Engraving and Printing.
In 2000, the Mint was responsible for the production of 28 billion coins. See United States Mint coin production for annual production values of each coin.
Responsible for protection of Mint facilities, employees and reserves is the United States Mint Police, a federal law enforcement agency.

Producing domestic, bullion and foreign coins;
Manufacturing and selling national commemorative medals;
Designing, producing, and marketing special coinage;
Manufacturing and selling proof and uncirculated coin sets and other numismatic items;
Safeguarding and controlling the movement of bullion;
Disbursing gold and silver for authorized purposes;
Distributing coins from the various mints to Federal Reserve Banks. Mintmarks

United States commemorative coin
Early United States commemorative coins
Modern United States commemorative coins
Bureau of Engraving and Printing