What survives, and what does not

The database carries one row for every one of the 2,192 days between 1 January 1860 and 31 December 1865, each saying whether the paper published that day and whether a copy has been found. That is deliberate. A database that holds only what was found cannot tell you what it is missing, and a register of casualties that cannot tell you what it is missing is a misleading document.

The Mercury stopped with the Union occupation of Charleston in February 1865 and did not resume until November 1866, after this study ends. The month of the suspension is certain; the date of the last wartime issue is not established here, so every date in February 1865 is left open rather than guessed at. Sundays are marked as days on which no issue is expected, that being the general practice of Charleston dailies, though it has not been confirmed date by date.

Legibility is not judged by eye. Each page is put through a real OCR pass and scored on how many of the long words it returns are real words — long words, because garbled text throws off short real words by chance. Clean English prose scores 83 per cent. Anything under 50 per cent is noise carrying the occasional real word.

The search was not confined to the Mercury. Newspapers.com’s public catalogue lists eight titles for Charleston, South Carolina, of which four cover any part of 1860–1865. Each was then looked for in the free archives.

The Library of Congress question was settled on 30 August 2026 and the answer is a clean negative. Chronicling America holds 7,793 digitised pages of Charleston newspapers and not one of them is the Mercury or the Courier. The same query returns 383 pages for a control title, so the nought is a real nought and not a broken search.

Worse for the wider project, Chronicling America has no Charleston paper of any name covering 1860 to 1864. The earliest wartime-window titles it holds — the South Carolina Leader and the Charleston Daily News — both begin in 1865, after the city fell. For the years this register is about, the free route is closed, and not only for the Mercury.

That leaves the subscription archives and the microfilm. Which is not a technical decision: it needs an account, and somebody to read what that account’s terms permit by way of systematic download. Nothing was signed into, and no paywall, access control or bot check was worked around in building this.