Songfacts®:

• This song is about a guy who works at a car factory and builds his own Cadillac by sneaking out one piece at a time in his oversized lunchbox. It goes according to plan until he puts it all together and realizes the parts are all from different model years, so he ends up with a kind of automotive chimera that has only one tail fin. But it didn't cost him a dime and everyone knows its him when they see it. Answering questions about it is a little harder - when asked where he got it, he says he picked it up at the factory because it's cheaper that way.
• This was written by the Nashville songwriter Wayne Kemp, whose credits include "Next in Line" by Conway Twitty and "I'll Leave This World Loving You" by Ricky Van Shelton.
  
  According to Johnny Cash: The Biography by Michael Streissguth, Kemp came up with the idea after hearing a (likely apocryphal) story about an airman in Oklahoma who pilfered parts from his base to make a helicopter. Kemp planned to record it himself, but when Cash's producer, Don Davis, heard the song, he convinced him to let Cash record it.
• "One Piece At A Time" was the first #1 Country hit for Johnny Cash since "Flesh and Blood" six years earlier, and his first appearance on the Hot 100 since "Kate" in 1972. He never again reached the top of the Country chart or hit the Hot 100.
• Johnny Cash had a knack for singing novelty songs like this one with a dry sincerity that brought out the humor. You can also hear it on his hit "A Boy Named Sue."
• To promote this song, Cash's label had a Nashville salvage yard assemble a Cadillac piece by piece as described in the lyric. It was taken to the House of Cash museum in Hendersonville, Tennessee, where Cash got in the driver's seat and posed for pictures. It remained on display in the museum until 1986, and was later destroyed.
• Michelle Shocked covered this for the 1988 album 'Til Things Are Brighter...A Tribute To Johnny Cash.