Discovered a Program/Playbill circa 1921 in my archive from another stop on the Orpheum Circuit, the Hennepin Theater in Minneapolis. On this bill, Harry Delf not only performed his notable comedy and dance routines but also wrote the headlining number, a "Dramatic Incident in Five Parts" titled "The Joker" featuring Silent Film star Ethel Clayton.
At the suggestion of a "Family Archive" reader in a comment to my post Continuous Vaudeville http://cityvoice.typepad.com/family_archive/2009/11/continuous-vaudeville.html I've made it my standard practice to search (Google, IMDB, IBDB and Wikipedia) the performers listed on these Program/Playbills that shared the stage with my Vaudeville relatives. As well as yielding many fascinating and unique stories, what I've learned from these searches has helped me put the Era into a broader historical context. While some of these performers haven't been household names for close to a Century, I would argue, they were the first generation pioneers and the origin of what we think of today as the Modern Entertainment Industry. Take Ethel Clayton for example from a quick search I learned: she was born in 1882 in Champaign Illinois. She started out as a stage actress eventually landing starring roles. She made her first film "Justified" a silent short in early 1909 and had 3 other credited roles that year. She was in the Ziegfeld Follies of 1911. The IMDB mentions her as having 189 credited and uncredited film appearances roughly 2/3 were in Silents. She made her last film appearance in 1947 in "The Perils of Pauline".
When you consider that Edison's "The Great Train Robbery", generally recognized as the first narrative film, came out in 1903 and Clayton's film career started in 1909 and lasted 38 years and that during this period she was performing on a stage with Fanny Brice and Bert Williams in the Ziegfeld Follies a few years after it was founded; for my money these seem like ample credentials to justify the status Pioneer of the Modern Entertainment Industry.