1878-S

San Francisco struck 140,000 quarters in 1878, a sharp drop from the 9-million-piece 1877-S output and the smallest S-mint Seated Liberty quarter mintage since the 80,000-piece 1859-S. The Bland-Allison Act of February 28, 1878 redirected San Francisco's silver capacity toward the new Morgan dollar program, and quarter production for the year fell to a small fraction of what the mint had been delivering in the run-up to the January 1879 Specie Resumption. The 1878-S therefore sits next to the 1878-CC as one of the two genuine Semi-Keys of the year and the last meaningfully scarce S-mint quarter before the design ended in 1891. Design remained the post-Arrows With Motto form: the motto "IN GOD WE TRUST" on the banner above the eagle, the S mintmark below the eagle, no arrows at the date, and the 6.25-gram weight standard from the Coinage Act of February 12, 1873.

What collectors examine on the issue starts with the mintmark. The S should read cleanly without evidence of recutting or addition, and the punch placement should be compared against verified-genuine 1878-S examples for the date, since low-mintage S-mint coins remain a target for mintmark addition to common 1878 Philadelphia hosts. Strike quality is typical San Francisco for the period, with the central shield horizontals and the eagle's right leg sometimes showing softness on late-die-state pieces. The drapery at Liberty's elbow should be cleanly defined on a problem-free coin. Authentication concerns are real at this mintage level; the safe baseline is certification from PCGS, the Professional Coin Grading Service, or NGC, the Numismatic Guaranty Company. A genuine planchet falls within tolerance of 6.25 grams.

Population data from PCGS and NGC clusters the issue in Fine through Very Fine, with Extremely Fine coins scarce and About Uncirculated examples genuinely difficult. Mint State survival is thin, and MS63 and above is a meaningful condition reach because so few unworn 1878-S quarters were preserved out of the routine commerce of the late 1870s and 1880s. The issue trades at firm premiums to common-date Philadelphia issues of the year at every grade level, and the gap widens through the upper end. For a date-and-mintmark set builder, the 1878-S is a recommended certified buy and one of the better-value Semi-Keys of the series in circulated grades. Original gray patina trades best. For the broader story of Gobrecht's design and the series' late-1870s production, see the Seated Liberty Quarter series history.