As early as 1956, the United States Army Nuclear Power Program had been researching and developing a compact nuclear power plant. These compact reactors would be movable on semitrailers, railroad flatcars, or barges. The January 15, 1958 United State House of Representatives record relates the following.

The Army’s Nuclear Power Program was heavily scaled back in 1966 because of budget cuts related to the Vietnam War. Nuclear power never found its way to any of the 6 Overland Trains.