The first season began and ended at midnight, and during its ninth episode (8:00 – 9:00 am) Jack mentioned that he had already been awake for 24 hours. In most subsequent seasons the story starts in the morning. Seasons two and seven began at 8:00 am, seasons four and five began at 7:00 am, and season six began at 6:00 am. This was a more realistic period of time for the characters to have been continuously awake. Season three began at 1:00 pm and season eight began at 4:00 pm.
The seventh season, originally scheduled to premiere on January 13, 2008, was postponed in the wake of the 2007–2008 Writers Guild of America strike. To ensure a nonstop season, a trademark of the show since the start of its fourth season in January 2005, the season was postponed a full year until January 2009. To help offset the strike-induced delay, the show returned on November 23, 2008, with a feature-length TV movie, 24: Redemption, that takes place nearly four years after season six and sets up the story that launched season seven.
Like the 1997 film Air Force One, 24 has featured Air Force One and use of the 25th amendment. Air Force One was featured in 24 Seasons 2 and 4. Air Force Two (carrying the Vice President but not the President) was featured in season 6. 24 used the same Air Force One set from the film. Seven actors featured in 24—Xander Berkeley, Glenn Morshower, Wendy Crewson, Timothy Carhart, Jürgen Prochnow, Tom Everett and Spencer Garrett—appeared in the film Air Force One.
The sixth season's two-night, four-hour premiere, broadcast in 2007, garnered the largest audience in 24's history, averaging 15.7 million viewers. Ratings peaked at one point to 16.3 million. By comparison, the precedent seventh season's two-night, four-hour premiere, broadcast in 2009, decreased slightly in viewers, averaging an overall 27 million viewers over the two nights.