 In 1904 he relocated to the United States and began working as a mine labourer in Denver, Colorado.In 1905 he moved to San Francisco, California, where he published the newspaper "Alba Roja" ("Red Dawn"); 
In May 1906 Guerrero was visited by Manuel Sarabia, who invited him to participate on the Organizing Committee of the Mexican Liberal Party (JOPLM).In addition to "Alba Roja", Guerrero worked on other papers, including "Revolución" (1908) and "Punto Rojo" (1909), 
which had a weekly print-run of 10,000 copies in El Paso, Texas, and joined its voice to calls for a general strike; 
he also contributed to "Regeneración", published by the Flores Magón brothers.