Question: longest-running scripted primetime tv series in the us
Answer: Number of seasons Series Network First air date Last air date Number of episodes 29 The Simpsons FOX 1989 - 12 - 17 Present 618 21 South Park Comedy Central 1997 - 08 - 13 Present 278 20 Gunsmoke CBS 1955 - 09 - 10 1975 - 03 - 31 635 20 Law & Order NBC 1990 - 09 - 13 2010 - 05 - 24 456 19 Law & Order : Special Victims Unit NBC 1999 - 09 - 20 Present 410 17 Lassie CBS 1954 - 09 - 12 1971 - 03 - 21 547 16 Family Guy FOX 1999 - 01 - 31 Present 289 15 NCIS CBS 2003 - 09 - 23 Present 330 15 CSI : Crime Scene Investigation CBS 2000 - 10 - 06 2015 - 02 - 15 335 15 ER NBC 1994 - 09 - 19 2009 - 04 - 02 331 15 T