What are the longest-running primetime television series?

The longest-running comedy (animated) is The Simpsons, which first aired winter of 1989, and is still going strong.  Other shows with hundreds of episodes behind them include COPS (over 650 episodes to date), Lassie (around 590 episodes), and Law & Order (over 400 episodes to date). 

Other popular and long-running shows include Watch Mr. Wizard (547 episodes), Bonanza (430 episodes), Knots Landing (344 episodes), ER (300+ episodes to date), Dallas (357 episodes), NYPD Blue (261 episodes), Murder, She Wrote (264 episodes), and Hawaii Five-O (284 episodes).

For half-hour sitcoms, the longest running include (in order of highest to lowest number of episodes) Cheers (at 273), Frasier, M*A*S*H,  Married with Children, Happy Days, The Jeffersons, Murphy Brown, and Friends (at 236).

The longest-running show of all time is Meet the Press (since fall, 1947).  The longest-running soap opera is Guiding Light (since summer, 1952).  The longest-running sports show is the Pro-Bowlers’ Tour (since 1962).  The longest-running children’s show is Sesame Street (since fall, 1969).  The longest-running game show is The Price is Right (since fall, 1972).