This Day In History May 20, 2005 On May 20, 2005, The Simpsons aired its 400th episode, earning the distinction of being the longest running series in television history. Not bad for a show that started as a cartoon used between sketches for a comedy series. Simpson’s creator Matt Groening got the gig on “The Tracey Ullman Show” in 1987 … Continue reading This Day in History: May 20th