Superman was a daily newspaper comic strip which began on January 16, 1939, and a separate Sunday strip was added on November 5, 1939. These strips ran continuously until May 1966. In 1941, the McClure Syndicate had placed the strip in hundreds of newspapers. At its peak, the strip, featuring Superman, was in over 300 daily newspapers and 90 Sunday papers, with a readership of over 20 million.