When did the Marvel Cinematic Universe U.S. presidential history diverge from the real world's?

Question

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.

Answer 1

Assumptions

The Marvel Cinematic Universe, which exists in Earth-199999 runs on the same Presidential Cycle as our Earth. That means that elections would've been held in 2008, 2012 and 2016 (with the elected President taking office on January 20th the following year).

The Presidents depicted in other media and flashbacks were personified as the actual Earth Presidents, not a caricature of their likeliness.

Arguments

Iron Man existed as a public figure starting in 2008. The MCU wikia calls this BIM and AIM (Before "I am Iron Man" and After "I am Iron Man"). AIM is essentially the kickoff of Phase One which concludes with the introduction of the Avengers. There are no references to a sitting US President during the Phase One films [source?]

The first reference in character of a sitting POTUS is President Matthew Ellis in Iron Man 3 (2013). Again if assuming similar election cycles, this means he was elected at the end of 2012 and took office in January 2013. the events in New York in The Avengers, at the end of Phase One.

As noted by the OP, there is a presiding argument that can still be made whether President Ellis was possibly already in office during the 2008 election cycle.

• He ran on a platform of "I will defend this country at all costs", in reference to the 2012 attack on New York.
• There is also the quote shown in the Smithsonian exhibit stating: "Welcome Back, Cap!" credited to Ellis during Captain America: The Winter Soldier (2014).

The argument here is when that quote was made. That thread makes the assumption that the quote was made by President Ellis in 2011 when Captain America was thawed (making Ellis the president during the 2008 cycle). However the argument can be made whether the quote is from 2011 at all. As it could be that the quote was made as part of an official acknowledgment from the government to the public that the Avengers exist, which might've been sometime after New York when Ellis first took office in 2013.

Conclusion

The creation of Earth-199999, the Earth that President Ellis is the POTUS, started with the creation of the MCU. It is a fair assumption when answering the OP's question that the MCU presidents diverge from the real Earth presidents at the MCU's creation, or rather, Earth-199999's creation.

There is no reference to President Obama in any of the films, and while there is no reference to George W Bush during the Iron Man film, he is doing business in Afghanistan which means that similar events in both universes happened that led to our involvement in the Middle East. So yes to GWB and no to Obama. 2008.

Answer 2

Runaways specifically mentions both Trump being the current President (by mentioning that the President is orange) and Nico states that “[her] parents haven’t had sex since the Obama Administration.”

Also, Iron Man 3 takes place in December 2012, BEFORE Inauguration Day meaning Ellis was ALREADY the POTUS.

In conclusion and assuming mostly the same Presidential elections as in the real world, the latest Obama could be President is 2005-2009, with Ellis elected in 2008 and 2012, and Trump elected in 2016.