Mint marks are the small letters stamped onto a coin to identify the US Mint facility that struck it. They look like a footnote, but they often determine whether a coin is worth face value or several thousand dollars. The 1909-S VDB Lincoln cent and the 1916-D Mercury dime are two of the best-known examples in American numismatics; both carry six-figure prices in top grades.
What the letters mean
US Mint facilities, current and historical:
- P — Philadelphia (the original mint, opened 1792)
- D — Denver (opened 1906) and earlier Dahlonega, Georgia (1838 to 1861, gold only)
- S — San Francisco (opened 1854)
- CC — Carson City, Nevada (1870 to 1893)
- O — New Orleans (1838 to 1909, with gaps)
- W — West Point, New York (modern bullion and commemoratives)
Philadelphia coinage carried no mint mark for most of US history. The exceptions are the wartime nickels of 1942 to 1945, which placed a large P above Monticello to identify the silver alloy used during WWII.
Where to look on common series
The location moved over time, often without warning. A few rules of thumb:
- Lincoln cents (1909 to date): Below the date on the obverse.
- Buffalo nickels (1913 to 1938): Reverse, below FIVE CENTS, beneath the buffalo's mound.
- Mercury dimes (1916 to 1945): Reverse, to the left of the fasces.
- Washington quarters (1932 to 1964 silver, 1965 to 1967 none, 1968 to date): Pre-1965 on the reverse below the eagle; 1968 forward on the obverse to the right of Washington's queue.
- Morgan dollars (1878 to 1921): Reverse, below the eagle's tail feathers, between DO and LLAR.
The pitfalls
Three errors come up constantly in raw coin assessment:
- Mistaking dirt or a die chip for a mint mark. Use 10x magnification and angled light. A real mint mark has crisp edges and even depth.
- Misreading a worn S as a 5 or B. Compare against a known reference image at the same grade.
- Missing the no-mint-mark variant. When the description says "no mint mark visible," that is a positive identification of a Philadelphia issue, not a defect.
What we do at USCNE
When operator intake records a date and mint mark, the AI identification is told to treat that as authoritative. The system flags any photo that contradicts the operator's note so a second look is forced before listing. For high-value certified examples, the cert number is queryable against the grading service's population reports as an additional check.
For consignors, this means accurate mint mark capture during intake directly affects your starting bid and the buyer-facing description. If you are unsure, leave it blank and let the operator confirm under magnification.