A coroner carried out the inquest days after lawman Wyatt Earp, his two brothers and Doc Holliday confronted a gang of drunken outlaws on October 26, 1881, leaving three of them dead.
The fight entered Wild West folklore and has been the subject of films and books including the 1957 movie starring Kirk Douglas and Burt Lancaster.
It was documented in detail during the inquest, which cleared the Earps and Doc Holliday of any blame for gunning down brothers Frank and Tom McLaury and Bill Clanton.
But the papers were mislaid half a century ago and only emerged when court clerks found them in a manila envelope, marked ‘keep’, while they were reorganising old files.
Officials showed off one page of the transcript yesterday, a thick sheet of paper with blue lines and sloppy writing in dark ink.
It appeared to contain the beginning of testimony by William Claiborn, identified by a historian as a friend of the three dead outlaws.