“The Simpsons” (Fox/© 2014 TCFFC)

“The Simpsons” has been airing for what feels like forever, so this may not come as too much of a shock: When FXX starts airing every single episode in a row beginning Thursday morning, it will shatter the record for the longest-running marathon in TV history.

The animated classic kicks off with the pilot from December 1989 at 10 a.m. The marathon continues through all 552 episodes, going all the way up to the 25th season finale that aired this past spring, and ends Sept. 1 at 11:30 p.m. Wedged between all the episodes is “The Simpsons” movie, which will be shown at 6 p.m. Aug. 29.

(Hint: You can check here to see if you actually get FXX on your cable provider.)

This is all leading up to the launch of syndicated “Simpsons” episodes that will air regularly on FXX starting after Labor Day. Plus, the October launch of the “Simpsons World” app available on multiple devices, which will allow users to watch any episode of the series anytime they want, and pull their favorite quotes and clips.

As The Post’s TV critic Hank Stuever wrote, “For better or worse, this will make the world a place inhabited by people who started playing around with ‘Simpsons World’ and never looked up from their iPads again.”

Anyway, the madness starts Thursday — you can find a detailed schedule of the marathon, but here’s when a few of the classic episodes will air.

“Krusty Gets Busted” (Thursday, Aug. 21 at 3:30 p.m.): In which we are introduced to Sideshow Bob.

“Stark Raving Dad” (Friday, Aug. 22 at 3:30 a.m.): The Tampa Bay Times points out that Michael Jackson once secretly voiced a character.

“Marge vs. the Monorail” (Friday, Aug. 22 at 9 p.m.): One of Conan O’Brien’s most famous works.

“Treehouse of Horror IV” (Saturday, Aug. 23 at 4:30 a.m.): Homer sells his soul for a doughnut, because who wouldn’t?

“Treehouse of Horror V” (Saturday, Aug. 23 at 4 p.m.): Time traveling toasters! (Maybe just watch all the “Treehouse of Horror” episodes.)

“Who Shot Mr. Burns?” (Sunday, Aug. 24 at 1:30 a.m.):  The sequel airs right after.

“Lisa the Vegetarian” (Sunday, Aug. 24 at 4 a.m.): Because “you don’t win friends with salad.”

“A Fish Called Selma” (Sunday, Aug. 24 at 11 a.m.): “Planet of the Apes” musical and Troy McClure.