The Simpsons (season 21)

The Simpsons' twenty-first season aired on Fox from September 27, 2009, to May 23, 2010. It was the first of two seasons that the show was renewed for by Fox, and also the first season of the show to air entirely in high definition. With this season, The Simpsons established itself as the longest-running American primetime television series surpassing Gunsmoke.

The Simpsons (season 21)

The Simpsons' twenty-first season aired on Fox from September 27, 2009, to May 23, 2010. It was the first of two seasons that the show was renewed for by Fox, and also the first season of the show to air entirely in high definition. With this season, The Simpsons established itself as the longest-running American primetime television series surpassing Gunsmoke.