Tombstone is a historic western city in Cochise County, Arizona, United States, founded in 1879 by Ed Schieffelin in what was then Pima County, Arizona Territory. It was one of the last wide-open frontier boomtowns in the American Old West. The town prospered from about 1877 to 1890, during which time the town's mines produced US$40 to $85 million in silver bullion, the largest productive silver district in Arizona. Its population grew from 100 to around 14,000 in less than seven years. It is best known as the site of the Gunfight at the O.K.