In the 1920s and 1930s, Oberhardt was among the best-known and most popular illustrators in the U.S. He portrayed impoverished immigrants, pushcart peddlers, child laborers and the Manhattan skyline for The East Side magazine, which Zoe Anderson Norris (1860-1914) published bimonthly starting in 1909.[2]
Among his formal portrait subjects were Presidents William H. Taft, Warren G. Harding and Herbert Hoover; the inventor Thomas Edison, the writer Ameen Rihani and the composer Sergei Rachmaninoff.
His portrait of Uncle Joe Cannon (Speaker of the House) from Time was placed on the top of the 1939 World's Fair Time Capsule, to be opened in 2039. Subsequently, he also drew President Harding for "Time". Additionally, he was well known for his advertising work and patriotic and recruiting posters in both world wars.[citation needed]