The story of John Henry, told mostly through ballads and work songs, traveled from coast to coast as the railroads drove west during the 19th Century. And in time, it has become timeless, spanning a century of generations with versions ranging from prisoners recorded at Mississippi’s Parchman Farm in the late 1940s to present-day folk heroes. —Carlene Hempel —John Henry: The Man – Facts, Fiction and Themes (ibiblio)
I’ve got a John Henry project I’ve been sitting on for several years… I’m planning to dig it out soon. This site has a good biography (which actually cites the online abstract of a talk I gave at the MLA years ago, though that was 3 websites ago.)
Update. 29 Jun: A few other nuggets: NPR (good bibliography), Garst (recent research claims Alabama, not West Virginia, as source of the legend).