That’s OK, Johnny Cash never shot a man in Reno either. Songs are just stories set to music. For some reason some people think they are all supposed to be autobiographies.
Johnny Cash's Folsom Prison Blues (1956) contains a number of curiosities. For one thing, why is he in prison in Folsom, Calif. for a crime he committed in Reno? And we can assume that this is Reno, Nevada, not Reno, Italy.
For another, the train in question is headed "on down to San Antone," but the only "San Antone" anywhere near Folsom is San Antonio Valley, south of Altamont Pass, which has never had rail service. In any case, Folsom may be on a rail line, but it is not a major one.
Perhaps Johnny Cash wanted to make "Folsom Prison Blues" sound like a real prison song that jumps from prison to prison as inmates who know it get released and then arrested and convicted in different jurisdictions, where they can teach the song to a new set of inmates.