ER is an American medical drama television series created by Michael Crichton that premiered on NBC on September 19, 1994. It was produced by Constant c Productions and Amblin Television, in association with Warner Bros. Television. The series follows the inner life of the emergency room (ER) of fictional Cook County General Hospital in Chicago, and various critical issues faced by the room's physicians and staff. During the course of the series, 331 episodes of ER aired over fifteen seasons, between September 19, 1994, and April 2, 2009.