The Penguin Book Of American Folk Songs, compiled and with notes by Alan Lomax, published in 1964, includes "Rock Island Line" with the following footnote:

    John A. Lomax recorded this song at the Cummins State Prison farm, Gould, Arkansas, in 1934 from its convict composer, Kelly Pace. The Negro singer, Lead Belly, heard it, rearranged it in his own style, and made commercial phonograph recordings of it in the 1940s. One of these recordings was studied and imitated phrase by phrase, by a young English singer of American folk songs [referring to Lonnie Donegan], who subsequently recorded it for an English company. The record sold in the hundreds of thousands in the U.S. and England, and this Arkansas Negro convict song, as adapted by Lead Belly, was published as a personal copyright, words and music, by someone whose contact with the Rock Island Line was entirely through the grooves of a phonograph record.

According to Harry Lewman Music,

    Lead Belly and John and Alan Lomax supposedly first heard it from [a] prison work gang during their travels in 1934/35. It was sung a cappella. Huddie [Lead Belly] sang and performed this song, finally settling on a format where he portrayed, in song, a train engineer asking the depot agent to let his train start out on the main line.[5]

Lonnie Donegan's recording, released as a single in late 1955, signaled the start of the UK skiffle craze. This recording featured Donegan, Chris Barber on double bass and Beryl Bryden on washboard. Pete Seeger recorded a version a cappella while he was chopping wood, to demonstrate its origins