<human>:  What is the history of the longest running TV show?
<bot>: The longest running TV show in history is the American police procedural drama series Law & Order. It premiered on NBC on September 13, 1990, and completed its 20th and final season on May 24, 2010. There were a total of 456 episodes produced during its 20-year run, making it one of the longest-running scripted primetime television series in the United States.