It's the greatest song ever written about sex on a train. (I don't even know if there's another song about sex on a train. Do you?)
It's a standard for all blues-rock bands. It was the first song that Led Zeppelin ever played.
Never mind your rock history books, but this is first song to use guitar distortion*, preceding not just the Kinks ("You Really Got Me") but even Link Wray ("Rumble").
Of the several gazillion versions of this song, there's one that still rocks ferociously.
Ladies and gentlemen, the Johnny Burnette Rock'n Roll Trio singing "Train kept a-rollin'". For best results, PLAY IT LOUD. (Sadly, not a video of the band. YT has plenty of other versions, including the famous Yardbirds' version. Guitarist Grady Martin's son has a comment on the YT page.)
*But who played lead? Was it Paul Burlison or Grady Martin? The debate, on this super-geeky guitar page.
*Also see this excellent WFMU page on "country-fuzz".