A key date coin is a specific date and mintmark combination within a U.S. coin series that was struck in significantly lower numbers than other years, making it considerably scarcer and more valuable than common issues in the same series.
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A practical reference for the dates and mintmarks that matter most across major U.S. coin series.
Rare coins in genuinely fine condition are among the most sought-after objects in American numismatics. They exist, but finding them requires decades of experience, extensive market knowledge, and the patience to evaluate hundreds of thousands of ordinary coins before encountering one that is truly exceptional. The key dates listed on this page represent the most significant rarities we encounter across every major U.S. coin series.
This is not an exhaustive rarity list. It is a practical reference built from over five decades of buying and selling coins in Upstate South Carolina. These are the dates and mintmarks that matter most and that we see most frequently in collections brought to our shop. If your coin does not appear here, that does not mean it is common or worthless. Many coins carry value above their face or melt worth, and even ordinary coins in certain conditions have a market. This list covers the best of the best.
For a broader understanding of what makes any coin valuable beyond these key dates, read our guide on how to know if your coins are valuable.
1856 to 1858
Key date: 1856
The 1856 Flying Eagle cent is one of the most historically significant pieces in American numismatics. Struck as a pattern to demonstrate the new small cent format to Congress, it was never officially released for circulation, making all known examples either pattern coins or later restrikes. Fewer than 2,000 are believed to exist. If you have one, it warrants immediate professional authentication.
1859 to 1909
Key date: 1877
The 1877 Indian Head cent stands as the undisputed key date of the series with a mintage of only 852,500 coins. The economic depression of the mid-1870s drastically reduced cent production. Even heavily worn examples carry significant collector premiums.
1909 to 1958
Key dates: 1909-S VDB, 1914-D, 1922 Plain (Missing D), 1931-S
The Lincoln cent series contains four dates of major significance:
The 1909-S VDB is the most famous key date in American coinage. When the cent was introduced, designer Victor David Brenner's initials appeared prominently on the reverse. Public backlash led the Mint to remove them after only 484,000 San Francisco examples were struck. 1909-S VDB Lincoln cent complete guide.1909-S VDB Lincoln cent complete guide
The 1914-D was struck in modest numbers during a period of reduced Denver production and is scarce in all grades above Fine.
The 1922 Plain results from a heavily worn die that eliminated the D mintmark entirely. Collectors specifically seek examples where no trace of the D is visible under any magnification.
The 1931-S was struck in low numbers during the Great Depression and hoarded by collectors at the time, making circulated examples common but uncirculated survivors genuinely scarce.
1866 to 1883
Key date: 1880
The 1880 Shield nickel had a mintage of only 16,000 pieces, making it among the scarcest regularly issued nickels of the 19th century. Most surviving examples were saved by collectors of the era, so well-worn circulated examples are actually harder to find than lightly circulated ones.
1883 to 1913
Key dates: 1885, 1912-S
The 1885 Liberty Head nickel had a low production year with only 1,472,700 struck, making it the key date of the series in circulated grades. The 1912-S is significant because San Francisco produced only 238,000 examples. This was the final year of regular Liberty Head nickel production before the Buffalo nickel replaced it in 1913.
1892 to 1916
Key dates: 1894-S, 1895-O
The 1894-S Barber dime is one of the most famous rarities in American numismatics with only 24 known examples. It belongs in a different category from any other coin on this page. If you believe you have one, professional authentication is essential before any transaction. The 1895-O had a mintage of only 440,000, making it the most elusive regular-issue date of the series.
1916 to 1945
Key date: 1916-D
The 1916-D Mercury dime is the unquestioned key date of the series with a Denver mintage of only 264,000 coins. Many have been counterfeited by adding a D mintmark to common 1916 Philadelphia examples. 1916-D Mercury dime complete guide.1916-D Mercury dime complete guide.
1892 to 1916
Key dates: 1896-S, 1901-S, 1913-S
All three San Francisco issues represent the scarcest dates in the Barber quarter series. The 1901-S is the most valuable in the group, with a mintage of 72,664 and virtually no surviving examples in collectible condition. The 1913-S had a mintage of only 40,000, making it the lowest production figure of any regularly issued Barber quarter.
1916 to 1930
Key dates: 1916, 1927-S
The 1916 Standing Liberty quarter was struck in the final weeks of the year with a mintage of only 52,000. The design was controversial and quickly modified, making first-year examples especially desirable. 1916 Standing Liberty quarter complete guide.1916 Standing Liberty quarter complete guide.
The 1927-S had a low San Francisco mintage and survivors in grades above Very Fine are exceptionally rare.
1932 to present
Key dates: 1932-D, 1932-S
Both branch mint issues from the first year of the Washington quarter are key dates. The 1932-D had a Denver mintage of 436,800 and the 1932-S had a San Francisco mintage of 408,000. Both are significantly scarcer than the Philadelphia issue of the same year.
1892 to 1915
Key date: 1904-S
The 1904-S Barber half dollar had a San Francisco mintage of only 553,038, making it the scarcest date of the series in uncirculated condition.
1916 to 1947
Key dates: 1919-D, 1921-D, 1921-S
The three key dates of the Walking Liberty half dollar series all share the characteristic of low branch mint production. The 1921-D and 1921-S are the most significant, with both having mintages under 250,000. Circulated examples of all three are collectible; uncirculated examples are genuinely rare.
1849 to 1889
Key dates: 1849-C, 1850-D, 1852-D, 1854-D, 1855-C, 1855-D, 1856-D, 1857-C, 1857-D, 1858-D, 1860-D, 1861-D, 1875
The Charlotte and Dahlonega gold dollars are among the most collected branch mint issues in American numismatics. Both mints closed at the start of the Civil War in 1861, and their combined output was always modest. The 1875 stands apart as a proof-only issue with fewer than 20 known examples.
1840 to 1907
Key dates: 1840-D, 1841, 1841-D, 1842-C, 1842-D, 1845-O, 1848, 1849-C, 1854-D, 1855-C, 1855-D, 1856-D, 1859-D, 1862-S, 1864, 1865, 1875
The 1841 Philadelphia issue, known as the "Little Princess," is one of the great rarities of American gold coinage with only a handful of known examples. The 1875 is again a proof-only date. The Dahlonega and Charlotte issues throughout the series are consistently scarce and avidly collected.
1908 to 1929
Key date: 1911-D
The 1911-D Indian Head quarter eagle had a Denver mintage of only 55,680 coins, making it the key date of this short series by a significant margin.
1854 to 1889
Key dates: 1854-D, 1854-O, 1855-S, 1857-S, 1860-S, 1873, 1875, 1876, 1877
The Three Dollar gold piece is an unusual denomination that was never widely accepted in commerce and was struck in small numbers throughout its existence. The 1873, 1875, 1876, and 1877 are proof-only issues. Branch mint examples from Dahlonega and New Orleans are among the most coveted pieces in the series.
1839 to 1908
Key dates: 1839-D, 1840-C, 1847-O, 1850-D, 1861-C, 1861-D, 1861-S, 1862-S, 1863-S, 1870-CC, 1871-CC, 1873-CC, 1874-CC, 1875, 1875-CC, 1875-S, 1876-CC, 1877-CC, 1878-CC
The 1861 branch mint issues reflect the chaos of the Civil War's opening months. The 1875 Philadelphia issue had a production of only 200 business strikes, making it among the rarest Liberty Head half eagles. Carson City issues from the 1870s are avidly collected for their frontier mint origin and consistently low mintages.
1908 to 1929
Key dates: 1909-O, 1929
The 1909-O is the only New Orleans Mint issue in the Indian Head half eagle series and had a production of only 34,200 coins. The 1929 is the final year of the series with a mintage of 662,000, most of which were melted following the 1933 gold recall. Survivors are genuinely scarce.
1838 to 1907
Key dates: 1838, 1839, 1841-O, 1842-O, 1849-O, 1852-O, 1855-O, 1855-S, 1857-O, 1858, 1858-S, 1859-O, 1859-S, 1860-S, 1861-S, 1862-S, 1863, 1863-S, 1864-S, 1865, 1865-S, 1866, 1867-S, 1869, 1869-S, 1870-CC, 1870-S, 1871-CC, 1871-S, 1872-CC, 1873, 1873-CC, 1874-CC, 1874-S, 1875, 1875-CC, 1876, 1876-CC, 1877-CC, 1878-CC, 1879-CC, 1879-O, 1882-CC, 1883-O
The Liberty Head eagle series spans nearly seven decades and includes branch mint issues from New Orleans, Carson City, and San Francisco that collectively represent some of the most collected pre-Civil War and Reconstruction-era gold coins. The 1875 Philadelphia issue is a proof-only date. Carson City issues from 1870 onward are especially popular with collectors drawn to the frontier mint's history.
1907 to 1933
Key dates: 1920-S, 1930-S
Both key dates of the Indian Head eagle series are post-World War I San Francisco issues that were struck in small numbers and largely exported or melted. Survivors are rare in any grade and command significant premiums.
1849 to 1907
Key dates: 1850-O, 1851-O, 1852-O, 1853/2, 1853-O, 1854-O, 1855-O, 1856-O, 1857-O, 1858-O, 1859, 1859-O, 1860-O, 1861-O, 1866-S, 1870-CC, 1871-CC, 1872-CC, 1873-CC, 1878-CC, 1879-CC, 1879-O, 1881, 1882, 1885, 1885-CC, 1886, 1891, 1891-CC
New Orleans double eagles from the 1850s represent early large gold coinage in American history, and many were melted or lost at sea. The 1853/2 overdate is a recognized variety. Carson City issues from the 1870s and later are consistently popular. The low-mintage Philadelphia issues of the 1880s and early 1890s are among the rarest business-strike double eagles of the 19th century.
1907 to 1933
Key dates: 1920-S, 1921, 1927-D, 1927-S, 1930-S, 1931, 1931-D, 1932
The Saint-Gaudens double eagle is widely regarded as the most beautiful coin ever produced by the United States Mint. The key dates listed here are all post-1920 issues that were struck in small numbers and largely melted following the 1933 gold recall order. The 1921 had a Philadelphia mintage of only 528,500, most of which were melted. The 1927-D, 1927-S, 1930-S, 1931, 1931-D, and 1932 are all legitimately rare coins with surviving populations in the hundreds or low thousands. Any of these dates warrants professional authentication before a transaction.
For a broader discussion of pre-1933 gold coin values and how condition affects pricing, read our pre-1933 gold coin values guide. Collectors comparing modern bullion issues can also explore our complete American Gold Eagles buying and selling guide, while sellers evaluating exceptional pieces can learn what distinguishes investment-grade coins with lasting collector demand.
Every coin on this page is evaluated on the three-factor framework that governs all numismatic transactions: date, mintmark, and condition. The date and mintmark tell us where a coin falls on the rarity spectrum. Condition determines where it falls on the value spectrum within that rarity tier.
For certified coins already graded by PCGS or NGC, the evaluation is straightforward. For raw ungraded coins, our evaluation draws on decades of experience and, when warranted, a recommendation to submit for third-party grading before a sale. Understanding the difference between graded and ungraded coins and how that affects your selling price is covered in our guide on ungraded, graded, and key date coins.
If your collection includes multiple categories, coins, silver, gold bullion, jewelry, or paper currency, everything is evaluated at the same appointment. If you inherited a collection and are not sure where to start, our guide on what to do with an inherited coin collection is a useful first read.
Cross-reference the date and mintmark on your coin against the list on this page. The mintmark is a small letter found on the obverse or reverse depending on the series and era. If your date and mintmark combination appears here, bring the coin in for evaluation. If it does not appear, the coin may still have value above face or melt, this list covers only the most significant rarities.
Yes, significantly. A key date coin in poor or damaged condition may still be worth a meaningful premium over a common coin, but condition determines how large that premium is. A key date in Fine condition and the same key date in Mint State condition can differ in value by a factor of 10 or more. Cleaned, polished, or damaged coins are always worth less than original, problem-free examples.
A key date is the scarcest issue in a series, typically commanding the highest premium. Semi-key dates are notably scarcer than common dates but not as rare as the key. Many semi-key coins appear regularly in collections and carry premiums that surprise sellers. Not every valuable coin is a key date.
Never clean a coin before bringing it in for evaluation. Cleaning, even gentle cleaning, permanently removes original surface and dramatically reduces value. A naturally toned, uncleaned coin is always worth more than a cleaned example of the same date and grade. Bring coins exactly as you found them.
Third-party grading services such as PCGS and NGC authenticate and grade coins in tamper-evident holders, providing a standardized, market-accepted grade. For common dates, grading is rarely worth the cost and time before selling. For genuine key dates, particularly in high grades, professional grading protects both the buyer and seller and often results in a higher realized price. We will advise you honestly on whether grading makes sense for your specific coins before any transaction.
Yes. This list covers the most significant rarities, but we buy coins across all categories including common silver, type coins, proof sets, commemoratives, colonial coins, and bulk collections. We need coins at every level, not just the rarest examples.
Clemson Coins, Currency and Bullion evaluates rare coins, key dates, and complete collections from sellers throughout Upstate South Carolina. Located at 7611 HWY 76, Pendleton SC 29670, we serve Pendleton, Greenville, Anderson, Clemson, Easley, Pickens, Lake Keowee, and Seneca, as well as northern Georgia, western North Carolina, and eastern Tennessee. All evaluations are free, all offers are made on the spot, and payment is immediate.
We evaluate rare coins and key date collections from sellers throughout the region, including Pendleton, Greenville, Anderson, Clemson, Easley, Pickens, Lake Keowee, and Seneca. We also work regularly with sellers from northern Georgia, western North Carolina, and eastern Tennessee. Call us first if the drive to our Pendleton location is not convenient and we can discuss your coins before you make the trip.
Clemson Coins, Currency and Bullion
7611 HWY 76, Pendleton, SC 29670
Call 864-502-0100