query: How many seasons did the show ER run?
passage: ER (TV series)
ER is an American medical drama television series created by novelist and medical doctor Michael Crichton that aired on NBC from September 19, 1994, to April 2, 2009, with a total of 331 episodes spanning over 15 seasons. It was produced by Constant c Productions and Amblin Television, in association with Warner Bros. Television. ER follows the inner life of the emergency room (ER) of fictional County General Hospital in Chicago, Illinois, and various critical issues faced by the room's physicians and staff. The show became the longest-running primetime medical drama in American television history, also became the 2nd longest medical drama across the globe (behind BBC's Casualty). It won 23 Primetime Emmy Awards, including the 1996 Outstanding Drama Series award, and received 124 Emmy nominations. ER won 116 awards in total, including the Peabody Award, while the cast earned four Screen Actors Guild Awards for Outstanding Ensemble Performance in a Drama Series.[1] As of 2014, ER has grossed over $3 billion in television revenue.[2]
passage: ER (season 4)
Chulack continued to serve as the series' most prominent director and helmed a further four episodes. Thorpe directed three more episodes. Charles Haid returned to the series for the first time since the first season to helm two episodes. New director Darnell Martin was the season's only other repeat director with two episodes. Other directors making their series debut with the fourth season were executive producer John Wells, Christopher Misiano, T.R. Subramaniam, and Sarah Pia Anderson. Regular directors returning to the series for single episodes include Jonathan Kaplan, Félix Enríquez Alcalá, Lesli Linka Glatter, and Thomas Schlamme. Cast member Anthony Edwards moved behind the camera to direct a further episode of the series. Editor Jacque Toberen and producer Lance Gentile each directed a single episode of the fourth season.