In preparation for the release of Captain America: Civil War, I've been watching all of the movies in the Marvel Cinematic Universe in order of release and I've noticed a few things about U.S. Presidents within the MCU.
Iron Man 3 introduced Matthew Ellis as POTUS, and according to this answer, he has been president since 2008 based on his quote "Welcome back, Cap" being in the Smithsonian as by President Matthew Ellis. However, the MCU wikia seems to imply that he was elected after the Battle Of New York, which means he would have been elected in 2012. This is further supported by his quote from Iron Man 3:
You elected me on a single platform: I will protect this country at all costs.
which wouldn't have been particularly relevant to say before the Battle Of New York, and probably would have read "re-elected" rather than "elected" if Ellis had been in office during the battle. Either way, this puts Matthew Ellis in office in either 2008 or 2012.
Now, in Captain America: Winter Soldier, in the scene where
Captain America and Black Widow discover an old S.H.I.E.L.D. bunker in New Jersey and activate the computer containing the uploaded brain of Hydra scientist Dr. Arnim Zola,
a clip montage of WWII plays on one of the computer screens and features, among clips of Captain America and the rest of the Howling Commandos, at least one shot of Franklin Delano Roosevelt. This leads me to believe that FDR's presidency happened in the MCU, though whether or not it ended as FDR's presidency did in the real world is likely up for debate.
This means somewhere between FDR's presidency, and the "current-day" presidency of Matthew Ellis, the MCU's presidential history diverged from the real-world presidential history. So, my question is, when did this happen? Was Matthew Ellis elected after George W. Bush, or if his first election win happened in 2012, after Barack Obama? Or did a fictional president get elected before that?
Edit: In Captain America: Civil War, Sharon Carter mentions that her great aunt, Peggy Carter, had her picture taken with JFK, so that seems to be a more recent president than FDR.