A mintmark is part of the coin design that tells which mint the coins were produced. Using mintmarks to identify where coins were made began in ancient Greece. Coins that were released into circulation were required to have a “Magistrate Mark,” a distinct mark representing the magistrate in charge of producing the coin. If a coin was to have problems, whether by accident or on purpose, the government knows who the responsible party was.
Mintmarks were first used in ancient times as a quality control mechanism. If a coin did not fit the specifications (under or overweight, not the right metal, etc.) it was easy to identify where the coin was made.
Another type of mark made on non-United State coin is a privy mark. A privy mark is a small design added to the coin to identify the where the coin was made, the coiner responsible for the coin, or some other aspect of the coin’s production for quality control purposes. Privy marks fell out of favor in modern times and countries with multiple branches use lettered mintmarks. Some mints use privy marks to differentiate different types of non-circulating legal tender coins.
Mintmarks used on United States coins are as follows:
The U.S. Mint was formally founded with the passage of the Mint Act of 1792. David Rittenhouse, the first Mint Director, was able to find a building in Philadelphia and begin operations in 1793. The first mint building served the country until 1833. The second mint building served from 1833-1901 and was demolished in 1902. The third mint was in service from 1901-1969. The building is now part of the Community College of Philadelphia. The fourth mint, located two blocks from the location of the first mint building, was opened in 1969 and continues to be used today. Up until 2009, it was the largest mint building in the world. However, no other mint in the world produces more circulating coinage than the Philadelphia mint.
All coins struck in Philadelphia from the founding of the Mint in 1793 until 1980 did not include a mintmark. The exception was the Type 2 Jefferson Nickels minted using the wartime alloy from 1942-1945. Coins struck using the silver-copper-manganese alloy feature a large mintmark above Monticello, including a “P” for Philadelphia.
In 1979, Susan B. Anthony dollars struck in Philadelphia included the “P” mintmark.
Beginning in 1980, all coins struck in Philadelphia, except for the Lincoln Cent, includes the “P” mintmark.
Charlotte became the first branch mint outside of Philadelphia. Authorized in 1835 following the gold strike at the Reed Gold Mine, it first became operational in 1838. The Charlotte branch mint was closed when the building was seized by the Confederacy during the Civil War in 1861. It was not reopened after the war. The Charlotte Mint’s “C” mintmark only appears on gold coins.
The Dahlonega Branch Mint was authorized by congress in 1837 after the Georgia Gold Strike. It opened for production in 1838. Like the Charlotte Mint, the Dahlonega Mint was seized by the Confederacy during the Civil War in 1861 and was never reopened. Gold coins dated 1838-1861 with the “D” mintmark were struck in Dahlonega. Coins with the “D” mintmark starting in 1906 were struck in Denver.
The branch mint at New Orleans was authorized by congress in 1836 as part of a discussion to make New Orleans a central trading gateway to the Midwest. This branch mint struck all denominations with the “O” mintmark. In 1861, the building was seized by the Confederacy and used by the Confederate government to strike coins. The Union Army recaptured New Orleans and the building in 1862. Unlike Charlotte and Dahlonega, the New Orleans Mint was eventually reopened. Its second life began as an assay office in 1876. With the passage of the Bland-Allison Silver Act of 1878, the building was refurbished to bring it back to coining standard and was used to strike silver coins, mostly dollars, until 1909. It was closed for the last time in 1909 with production down and Denver taking over the production load.
The San Francisco branch mint was opened in 1854 to assay and coin gold discovered during the California Gold Rush. The first building, known as the “Granite Lady,” was one of the few buildings to survive the Great San Francisco Earthquake of 1906. During the aftermath of the earthquake, Superintendant Frank Leach helped local residents by allowing them to use the grounds as a refuge. A new building was opened in 1937 and celebrated its 75th anniversary in 2012. Today, the Granite Lady is being refurbished as the Museum of San Francisco.
San Francisco produced circulating coins with the “S” mintmark until 1955 when production was suspended and the facility was “downgraded” to an assay office. Production of proof coinage was transferred to San Francisco in 1968 and they began to strike some coinage for circulation until 1974. Since 1975, San Francisco produced only proof coins along with cents without mintmarks to supplement production from Philadelphia. It is not possible to distinguish from no mintmark cents from either mint. San Francisco also produced circulating Susan B. Anthony dollars 1979-1981 with the “S” mintmark. They were granted mint status in 1988.
After the major discovery of silver as part of the Comstock Lode in what is Virginia City today, politicians lobbied congress for the formation of a branch mint to assay and strike coins. Congress authorized a mint in 1868 for nearby Carson City and the building was opened for production in 1870. The Carson City branch mint struck silver and gold coins but in lesser amounts than the other mints, making their coins highly collectible and more expensive because of their rarity. The “CC” mintmark is the only two-character mintmark used on U.S. coins.
Production ended in 1893 with the reduced production from nearby silver mines. Starting in 1895 the building served as an Assay Office until the gold recall of 1933. The building was sold to the State of Nevada in 1939 and was turned into the Nevada State Museum.
During the Pikes Peak Gold Rush, congress authorized the opening of a Denver assay office in 1863. Congress authorized the building of a branch mint in 1896 and construction began in 1898. Operations from the assay office were transferred to the new building in 1904 and the mint started to strike circulation coins in 1906. Denver struck gold coins until 1933 when gold was recalled. All coins with the “D” mintmark struck since 1906 were minted in Denver. Earlier gold coins dated 1838-1861 were struck in Dahlonega, Georgia.
In 1937, the Treasury built a facility on the northern part of the campus of the U.S. Military Academy to store silver. Originally, it was called the West Point Bullion Repository and was nicknamed as “The Fort Knox of Silver.” From 1968-1973, West Point produced cents without a mintmark in order to supplement the production from Philadelphia. They also produced Bicentennial and Washington Quarters 1975-1979 without mintmarks.
The “W” mintmark first appeared on the 1983 Olympics Commemorative Coins. West Point produces coins for the American Eagle Bullion program without mintmarks but produces collectable versions of the American Eagle with the “W” mintmark. Other commemoratives have been struck at West Point that includes the “W” mintmark.
The same bill that returned the San Francisco branch mint back to mint status in 1983 granted mint status to the West Point branch mint.
After the Philippines became a colony of the United States, the U.S. Mint established a branch mint in Manila. It is the only branch mint outside of the continental United States. The mint opened in 1920 and produced coins in one, five, ten, twenty, and fifty centavo denominations. Coins struck by this mint bear either the “M” mintmark or no mintmark.