With Avengers: Endgame deep in post-production for its wide release in April, one of the Marvel Studios sequel's many lingering mysteries is its official runtime. As the film must not only resolve the massive cliffhanger of Avengers: Infinity War, but also lay the foundation for the next phase of the Marvel Cinematic Universe, there's a lot of ground to cover, which means two hours isn't likely enough to do the story, or the characters, justice.

At 156 minutes, Infinity War has the longest runtime of any MCU film to date, but co-directors Joe and Anthony Russo have repeatedly hinted that Endgame is on track to reach three hours, or 180 minutes. That assertion was made as early as November, with Joe Russo admitting a rough cut had an approximate three-hour runtime, which he reaffirmed following the release of the first trailer. Should that estimate be maintained for the final cut, it would make Avengers: Endgame not only the longest installment of the MCU, but the longest superhero film to receive a wide theatrical release in the United States.

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Currently, the longest American superhero film is 2012's The Dark Knight Rises, at 164 minutes, followed closely by 2009's Watchmen, at 162 minutes. The longest film in the DC Extended Universe is 2016's Batman v Superman: Dawn of Justice, which clocks in at 151 minutes, a runtime to date only surpassed in the MCU by Infinity War.

While Watchmen did receive two extended home video releases, with a director's cut running for 186 minutes and an ultimate cut reaching 215 minutes, neither version received a wide theatrical release. The same home media-only technicality holds true for Batman v Superman's ultimate edition, with a runtime of 182 minutes.

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Outside of the United States, Endgame would lag behind a pair of Indian superhero films that each run for well over three hours: 2009's Kanthaswamy, which clocks in at 190 minutes, and 2011's Velayudham, which comes in close behind, at 186 minutes.

Nearly two months until the premiere of Avengers: Endgame, there is still a multitude of questions about the film. Historically, a film's runtime isn't disclosed until about a month before its theatrical release after it's submitted to the Motion Picture Association of America for its official rating. With that in mind, Avengers: Endgame's runtime will likely not be confirmed until sometime in March. But, if the Russo brothers' previous claims hold true, it will set a completely different kind of bar for American superhero films in length alone.

Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Chadwick Boseman, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film arrives on April 26.