The Dems need an autopsy -- they are now a completely regional party.

[JJC]

Just saying, after the 2008 Elections, the GOP was deemed as a regional party also..

People are overthinking results.

Nope, the Dems are trending away from winning the EC. Their ratio of number of votes to EC votes gets worse and worse...Repubs get better and better.

I don't know if that's true or not, but I do know that Dems have a massive geographical problem. Couldn't find a 2016 map, but here's 2012's map by counties where Obama won by 4 points nationally:


As you can see, dems won big in the coastal areas and cities, and pretty much nowhere else. Because they have so many of their voters confined to small regional areas, it does seem plausible that it would put them at a distinct electoral disadvantage. For example, Hillary won the pop vote because she banked a ridiculous amount of votes in CA (3.5 million more than Trump). But of course, the EV doesn't care if you win a state by one vote or ten million. All of the EV's go to the victor regardless.

So essentially, that's 3.5 million votes wasted that could have gone to more crucial areas of the country.

In contrast, GOP votes are spread out far more efficiently (especially Trump's).

[JJC]

Democrats consistently win more votes than Republicans.  Their votes are just less spread out.  As time goes on and demographics change, Democrats will win by wider and wider margins overall, and though their vote is more concentrated, it will eventually spread out just as it did from DC to VA/MD, which has made those two states Lean/Safe Dem.  This will happen in Georgia, Arizona, and Texas.  Democrats have a mortal lock on the Northeast and West Coast, so all they need to do is wait for more states to turn based on demographic changes... as has already happened in the Southwest + Virginia. 

I don't remember who said it, but I remember hearing the phrase "any attempt to create a permanent majority is doomed to failure."

People change. Cultures change. World events change our perceptions. And any time you aggressively push to gain one voting block, you will inevitably end up pushing away another. Dems tried to make a permanent majority by stitch-patching a multitude of minority and special interest groups. But this identity based venture ended up turning away the one group they weren't courting (and often the one blamed as all of the minority groups problems) - white voters.

@Nate_Cohn
How to think about this election: white working class voters just decided to vote like a minority group. They're >40% of the electorate.

Newton's third law. Every action has an equal and opposite reaction. For example, Dems courting Latinos by advocating open borders/no deportations invariably pushed away people most devastated by illegal (and legal) immigration - white working class voters. 

Dems efforts may indeed get them some minority-heavy southern states in the future. But I'll bet that by the time that happens, some white-dominated, northern-rust belt states like WI, MI, PA, NH, OH, and IA will become staple light red states by then.

There's also the issue of proceeding generations of voters (particularly latinos) becoming more Republican as they Americanize (they identify less with their nation of origin and more as simply American.