Is "Cross Road Blues" a historical account, a metaphorical vision, or the makings of an influential bit of satanic folklore? The best thing about the writing seems to be that it can still be interpreted as all three.
As a historical account, some have suggested that "Cross Road Blues" is actually about Johnson's anxiety about being a Black man out alone on the side of the road at night. The song, they say, reflects a fear of violence from white people in the rural, Depression-era south.
Trying to hitch a ride at night in rural Mississippi—where, as Johnson's friend Johnny Shines said himself, it was "open season on black people" (source)—could certainly be dangerous. And most African Americans didn't have cars or enough money to travel by train. Traveling musicians like Johnson regularly hopped freight trains and hitched rides, despite the danger, quite simply because they had no choice. The fear of racist violence, including lynching, was very real, and became the subject of other important songs from that era.
But in this case, reading the song as a literal account about hitchhiking probably underestimates Johnson as a songwriter. We think Johnson's songs are more like works of literature than accounts of history. In The Old Man and the Sea, Hemingway uses an old man's struggle with the natural world as an extended allegory for the human struggle with identity and memory. Life of Pi, Yann Martel's tall tale about a little boy stranded on a raft with a Bengal tiger, becomes a tale about perseverance, trauma, and the power of storytelling.
If we read the song as a metaphor, a crossroads is a site of crisis and suffering, where Johnson goes to God for mercy and to try to "flag a ride" to a new phase in his life.
Johnson was a strong metaphorical songwriter, so the idea that the song's about a metaphorical crossroads is pretty feasible. But he also knew that there was longstanding southern lore about the crossroads. A story about a pact with the Devil at the crossroads was already associated with other blues musicians, including Tommy Johnson, an older contemporary of Robert's. The (Christian) idea that musicians, especially blues musicians, were no-good troublemaking hobos who did the Devil's work contributed to the individual stories of possession and nighttime pacts.
No one is sure whether Johnson ever affirmed, repeated, or even knew about the Devil legend. But at least some have said that Robert Johnson did little to distance himself from the fantastic tale that he sold his soul at the crossroads. Instead, he played it up, according to the documentary The Search for Robert Johnson.
It seems he told his ex-girlfriend Willie Mae Powell that the rumors were true. He may have told other girlfriends the same thing, but first-person records of Johnson's life are hard to come by. Other songs of his, like "Me and the Devil Blues," do more than just hint that Johnson communed with Satan. It's this last interpretation of the crossroads that's the most widely accepted even if it's the least plausible.
Johnson's old friend Honeyboy Edwards gives us a way out of the conundrum, saying, "It may be Robert could have sold himself to the devil. In the way he was, the way he played and acted, he could have felt that he sold his soul. A special feeling could have hit him like he done that and that feeling come out in his music." (Source)
The legend has emotional truth, if not literal truth, and for those who want to make Johnson's poetry into Johnson's biography, the literal truth is still a possibility.