Bob Rosenberger, a major collector of vintage gambling memorabilia, emailed me that the brochure likely dates from 1904-1910. He says, "George Mason, Denver, was at the 1908-10 Lawrence St. address from 1904 to 1921. My guess is that the brochure dates from the 1904-1910 period based on their selling Harris checks and their use of 4-color printing. They first appeared in 1892 at 1713 Larimer in Denver."

Robert