The answer, up front: the letters and the mints
A mint mark names the branch mint that struck the coin. The United States ran several mints at once, and each one signed its work — except the first mint, which usually signed nothing. These are the marks a North American jar can hold:
| Mark | Mint | What to know |
|---|---|---|
| (none) | Philadelphia | The original mint. For most of its history it used no letter at all — on an older American coin, no mark is itself a mark. |
| P | Philadelphia | The home mint, signing. Look for it on larger modern coins — and, oversized, on the wartime nickels below. |
| D | Denver | Striking coins since 1906 — the workhorse mint of the modern West. |
| S | San Francisco | Struck the West’s coins from Gold Rush days; today it mostly makes proof and collector issues. |
| W | West Point | The newest mint of the group; mostly bullion and collector coins. |
| O | New Orleans | Struck from 1838 to 1909. Its silver dollars are collector favourites. |
| CC | Carson City | Struck beside the Comstock silver from 1870 to 1893 — the most chased mark on a Morgan dollar. |
Why should the mint matter? Because each mint struck its own number of coins in a year, and the numbers were rarely close. The letter points at a mintage — and mintage is where scarcity comes from, and scarcity is where price comes from.
Same design, same year, same wear — the letter can still make them two different coins.
The story: a return address in metal
In the early republic there was one mint, in Philadelphia, and its coins needed no signature: they could only have come from one place. Then the country spread out. Gold turned up in the South, then in California; silver poured out of Nevada. Hauling bullion across a continent to Philadelphia was slow and risky, so Congress planted branch mints near the metal — New Orleans in 1838, San Francisco in 1854, Carson City in 1870, Denver in 1906.
Every branch was ordered to stamp its initial on what it struck. The letter was accountability, not decoration: if a run of coins came out light or badly made, Washington knew whose door to knock on. Philadelphia, the home mint, simply never adopted the habit — which is why no mint mark on an old American coin does not mean a missing mark or a striking error. It means the coin came home.
The branches lived very different lives, and the letters carry them. Carson City struck for barely two decades beside the Comstock Lode, then went quiet. New Orleans worked for seventy years — even striking coins for the Confederacy in 1861 — before it closed in 1909. West Point is the newcomer, striking mostly bullion and collector pieces. A coin jar holds all of that history in letters a few millimetres tall.
What this means for your jar: where the letters hide
Every design keeps its letter in its own spot, and no two of the jar staples agree on one. Learn these four, plus the Canadian exception:
- Morgan dollar — the back, below the wreath. Flip the coin over: the mark sits just above the DO in DOLLAR. O, S, D or CC — or nothing, for Philadelphia. It is the first thing our Morgan dollar page checks, and a CC there changes the conversation completely.
- Lincoln cent — the front, under the date. A small D or S hides below the year; nothing means Philadelphia. On a 1909 cent, check the bottom of the back too: an S under the date plus the designer’s initials, V.D.B., on the reverse is the famous 1909-S V.D.B.
- Mercury dime — the back, low beside the rods. The mark sits at the lower left of the fasces, the bundle of rods on the reverse. Most 1916 dimes carry no mark and are worth a few dollars; a 1916 with a D in that spot is the key date of the whole series.
- War nickel, 1942–45 — the back, above the dome, impossible to miss. These nickels carry a large P, D or S over the building on the reverse; no other Jefferson nickel puts its mark there. The big letter does double duty — it also proves the coin is the 35% silver wartime issue, the same coin Guide 3 teaches you to spot by its edge and date.
- Canadian coins — usually no letter at all. Jar-era Canadian coins were struck in Ottawa, at one mint, and generally carry no mint mark; our Voyageur dollar page says it in one line: “No mint mark — all Canadian dollars were struck in Ottawa.” On a Canadian coin, no letter is normal — not a flaw, and not a rare error.
Reading one without hurting the coin
- Light and magnification, nothing more. Angle the coin under a lamp until the spot shadows, then use a loupe or a phone’s macro mode. Every mark above was placed to be read, not excavated.
- Never clean to reveal it. Do not wipe, scratch or polish at the spot hoping a letter will appear. A cleaned coin loses more than any letter can add — Guide 4 is the whole argument.
- Respect the famous letters. The marks worth real money are exactly the marks that get faked: our coin pages warn that added and altered mint marks are the most common fake in the 1916-D dime, the 1909-S V.D.B. and the CC Morgan alike. If the letter is what makes a coin valuable, that is precisely when a dealer’s or grader’s eyes earn their fee.
- Record the date and the letter together. The sorter prices a coin by the pair — a year on its own is only half the coin’s name.
Most letters in most jars will be the common ones, and there is no shame in that: the letter is how a coin tells you which door it walked out of — and some of those doors closed a century ago.
The date tells you when. The tiny letter tells you where — and sometimes where is where the money is.