Denver typographical union The lst Labor Union organized in Colorado on April 12, 1860. Wharton, - History _of Denver p.71 Help given by Mr. Byers. Georgetown Miner May 12, 1877 p.2 History and organization of Denver Typographical Union. Typographical Annual v.1 #1 Feb. 22, 1892 p.1 Charter member dies (Chas. S. Semper). Trail Magazine . v.10 #6 Nov.% 191' p.29 See also Clips: Colorado. Printing Colorado labor story. RMN April 19} 1959p.45A Centennial Edition)