"The Simpsons" became the longest-running scripted primetime show in U.S. history when it surpassed "Gunsmoke's" 20-season run. But when that happened . . . NINE YEARS ago now . . . "Gunsmoke" still had a massive leg-up in total number of episodes. But now, "The Simpsons" will surpass that, too.
On March 31st, 1975, "Gunsmoke" aired its 635th and final episode, and this Sunday "The Simpsons" will hit episode #636. The show is now in its 29th season. It premiered on Fox in December of 1989.