 After "The Masses" was banned from the U.S. Mail in 1917, due to its unflinching anti-militarism, Gropper joined artists like Robert Minor, Maurice Becker, Art Young, Lydia Gibson, Hugo Gellert, and Boardman Robinson in contributing to its successor, "The Liberator".Gropper also contributed his art to "The Revolutionary Age", a revolutionary socialist weekly edited by Louis C. Fraina and (in later issues) John Reed, a publication which narrowly predated the establishment of the American Communist Party, as well as to "The Rebel Worker", a magazine of the Industrial Workers of the World, an anarcho-syndicalist union.In 1920, Gropper went to Cuba briefly as an oiler on a United Fruit Company freight boat.