A few factors were at play, both at the time of the gunfight, and several decades later. To start, though, let’s look at when the gunfight at the OK Corral took place, and what was going on in the U.S. at that time. When the incident took place in late-October of 1881, it was a sensation for several reasons. First, locally, the conflict was the culmination of a long-running feud between two factions: the Earps and the Clanton-McLaurys. Tensions had been building between the two sides for some time, and when it finally erupted, many saw it as the somewhat logical conclusion of a feud that many thought was going to end in bloodshed one way or another. Newspaper reports immediately after (and the subsequent trial) made extensive use of primary reports outlining the ongoing dispute between the two sides, and how threats from each party had only grown and become increasingly violent. The fact that it led to a violent confrontation didn’t seem to surprise many people. What did surprise people was how formal the whole thing was! Most of the violence of Tombstone and other rough towns like Abilene or Dodge City involved extremely short, sudden outbursts of gunfire, often via ambush. The O.K. Corral incident involved a long walk through town to the site of the conflict (so everyone knew SOMETHING was about to pop off), verbal sparring, and then a full-throttle gun battle that actually lasted more than a couple of seconds. All of this was extremely rare for gunfights, and made for a very dramatic scene.

The conflict also represented an ongoing conflict within the country between established, civilized factions (the Earps, banks, railroads) and the free-wheeling Manifest Destiny spirit of many western inhabitants. The incident became emblematic of a larger issue at play, one that was exacerbated by identifications people made between the establishment (pro-Union) side, and the anti-establishment (pro-Confederacy sympathies).

Now, this in and of itself wouldn’t have necessarily immortalized the incident, but the fact that the gunfight at the O.K. Corral fit into many of these dramatic conventions, and the fact that Dime Novels, the cheap pulp literature of the day, played up just these kinds of conventions, put the whole thing into a special category. Dime novels were exaggerated, heavily-fictionalized literary accounts of life in the “wild west,” and many of them featured set-piece gun battles somewhat similar to the O.K. gunfight. It would be like if a major terrorist attack in 2017 was actually thwarted by a team of crime fighters in superhero outfits. It was the marriage of popular fiction and reality, and people ate it up.

Still, even with all that, after a few years, it had kind of faded out of popular memory, and outside of southern Arizona, there weren’t that many people talking about it. The reason why people know about it today is because Wyatt Earp lived to be 80 years old, and in the last few years of his life, while living in Los Angeles, he became friends with several people in the burgeoning film industry, and gave several interviews with a writer named Stuart Lake. Lake eventually wrote a book about Earp and his exploits, which was heavily influenced by Earp’s wife, who wanted nothing more than to present her husband as a white-knight hero of the old west. The iconic, seemingly-outlandish (Dime Novel-esque) nature of the incident at the O.K. Corral combined with a resurgence of interest in westerns within the new movie medium all came together at the perfect moment to catapult the gunfight at the O.K. Corral into legend. For most audiences, the gunfight at the O.K. Corral was brand new, and exciting (as mentioned before, by the 1930s, most people had forgotten about it), so it really took off. When the incident was colored in with details from the rest of Earp’s life (Dodge City, the vendetta ride), a legend was sort of re-born.

[Sources: Richard Slotkin, ‘Gunfighter Nation’; Michael Denning, ‘Mechanic Accents’]