From Chris Berry #3

Ringling_Barnum_EQUESTRIAN_(c1934)%20One_Sheet_Up, a photo by bucklesw1 on Flickr. Circus Press Agent and Artist Roland Butler created this poster for the Ringling Bros and Barnum & Bailey Circus in the mid 1930s (the design also appeared as the cover of the 1937 program book). Although this image was one of those which Acme would have claimed as being in "public domain" and available for reproduction, it is interesting to note that all of the Ringling-Barnum posters created after about 1942 were copyrighted by Ringling Bros and Barnum and Bailey - not the poster company. That allowed the circus to renew and protect their copyright on such classic images as the Lou Jacobs "See You at the Greatest Show on Earth" and the Lawson Woods' monkey circus posters.