From the site:
The idea for the Highwaymen came about in 1984 when Cash wrangled Nelson, Kristofferson and Jennings to film Cash's Christmas special in Montreux, Switzerland. Inspired by the camaraderie in the hotel, where they'd jam after long days on the set, the artists returned to the States and entered the studio with producer Chips Moman, eventually taking Webb's "Highwayman" as both their name and the title of the album. "It was a creative formula that worked," says John Carter Cash, who recalls Glen Campbell, Marty Stuart and Johnny Rodriguez present during those early sessions. Rodriguez, in fact, would lend his voice to the LP's "Deportee (Plane Wreck at Los Gatos)," a Woody Guthrie song.