According to legend, as a young man living on a plantation in rural Mississippi, Robert Johnson was branded with a burning desire to become a great blues musician. He was "instructed" to take his guitar to a crossroad near Dockery Plantation at midnight. There he was met by a large black man (the Devil) who took the guitar and tuned it. The "Devil" played a few songs and then returned the guitar to Johnson, giving him mastery of the instrument. This was in effect, a deal with the Devil mirroring the legend of Faust. In exchange for his soul, Robert Johnson was able to create the blues for which he became famous. 
This legend was developed over time, and has been chronicled by Gayle Dean Wardlow, Edward Komara and Elijah Wald, who sees the legend as largely dating from Johnson's rediscovery by white fans more than two decades after his death. Son House once told the story to Pete Welding as an explanation of Johnson's astonishingly rapid mastery of the guitar. Welding reported it as a serious belief in a widely read article in Down Beat in 1966. Other interviewers failed to elicit any confirmation from House and there were fully two years between House's observation of Johnson as first a novice and then a master.
Further details were absorbed from the imaginative retellings by Greil Marcus and Robert Palmer. Most significantly, the detail was added that Johnson received his gift from a large black man at a crossroads. There is dispute as to how and when the crossroads detail was attached to the Robert Johnson story. All the published evidence, including a full chapter on the subject in the biography Crossroads by Tom Graves, suggests an origin in the story of Blues musician Tommy Johnson. This story was collected from his musical associate Ishman Bracey and his elder brother Ledell in the 1960s. One version of Ledell Johnson's account was published in David Evans's 1971 biography of Tommy, and was repeated in print in 1982 alongside Son House's story in the widely read Searching for Robert Johnson.
In another version, Ledell placed the meeting not at a crossroads but in a graveyard. This resembles the story told to Steve LaVere that Ike Zimmerman of Hazelhurst, Mississippilearned to play the guitar at midnight while sitting on tombstones. Zimmerman is believed to have influenced the playing of the young Robert Johnson. Recent research by blues scholar Bruce Conforth uncovered Ike Zimmerman's daughter and the story becomes clearer. Johnson and Zimmerman did practice in a graveyard at night because it was quiet and no one would disturb them, but it was not the Hazlehurst cemetery as had been believed. Johnson spent about a year living with and learning from Zimmerman, who ultimately accompanied Johnson back to the Delta to look after him. Conforth's article in Living Blues magazine goes into much greater detail. There are now tourist attractions claiming to be "The Crossroads" at Clarksdale and in Memphis.
His own account
Most musicians who knew Johnson well, such as Johnny Shines, never heard him claim that he had sold his soul to the Devil. Different accounts give contradictory information in this regard, but there is no conclusive evidence one way or another.
"Me And The Devil" begins, "Early this morning when you knocked upon my door/Early this morning when you knocked upon my door/And I said, 'Hello, Satan, I believe it's time to go,'" and continues with, "You may bury my body down by the highway side/You may bury my body down by the highway side/So my old evil spirit can catch a Greyhound bus and ride."
Johnson's lyrics to "Cross Road Blues" ("Standin' at the crossroads, tried to flag a ride") suggest he was hitchhiking rather than selling his soul to the Devil.
The Devil in these songs may not solely refer to the Christian story of Satan, but equally to the African trickster god, Legba, himself associated with crossroads—though author Tom Graves deems the connection to African deities tenuous. As folklorist Harry M. Hyatt discovered during his research in the South from 1935–1939, when African-Americans born in the 19th or early-20th century said they or anyone else had "sold their soul to the devil at the crossroads," they had a different meaning in mind. Ample evidence indicates African religious retentions surrounding Legba and the making of a "deal" (not selling the soul in the same sense as in the Faustian tradition cited by Graves) with this so-called "devil" at the crossroads.
"The Blues and the Blues singer has really special powers over women, especially. It is said that the Blues singer could possess women and have any woman they wanted. And so when Robert Johnson came back, having left his community as an apparently mediocre musician, with a clear genius in his guitar style and lyrics, people said he must have sold his soul to the devil. And that fits in with this old African association with the crossroads where you find wisdom: you go down to the crossroads to learn, and in his case to learn in a Faustian pact, with the devil. You sell your soul to become the greatest musician in history."
Folk tales of bargains with the Devil have long existed in African-American and European traditions and were adapted into literature. Two well-known examples are Washington Irving's "The Devil and Tom Walker" in 1824 and Stephen Vincent Benet's "The Devil and Daniel Webster" in 1936. In the 1930s Hyatt recorded many tales of banjo players, fiddlers, card sharks, dice players, guitarists, and one accordionist selling their souls at crossroads. Folkorist Alan Lomax considered that every African American secular musician was "in the opinion of both himself and his peers, a child of the Devil, a consequence of the black view of the European dance embrace as sinful in the extreme".