NBC has renewed Law & Order for a 20th season! Previously Gunsmoke held the title for the longest running TV prime-time drama (from 1955-75), but now it's a big fat tie. Congrats Law & Order, you're officially tied with a western. You know what's crazy? As much as I say I hate shows like Law & Order, every time I accidentally turn on an episode I can't stop watching...just goes to show that courtroom shows work.