Take a look at this map...

...of the 1964 presidential election. That was a blowout, wasn't it? As you can see, Lyndon Johnson carried Utah, Wyoming and Oklahoma, the three states that gave Mitt Romney his greatest margins in the last election.

Now take a look at this one, from the 1972 election just eight years later:

Another blowout! Except this time it was the Republican's turn. In almost a mirror image, Richard Nixon carried Hawaii, Vermont and New York, President Obama's best states in 2012.

Finally, take a good look at this map from the last election (click on it to enlarge):

Why? Because this year's will probably look a lot like it.

Paul Waldman has a good piece in The Week, "The 2016 race could be a lot closer than you think," in which he argues rather persuasively that, well, the 2016 race could be a lot closer than you think. (But Hillary will still win.) He reasons, and I agree (my emphasis):

The vast majority of Republicans will cast their ballots for Trump, even if he's not the person they wish he would be.

Take my oldest brother and my sister, for example. I can pretty much guarantee that they'll both hold their noses and vote for the Donald. (Even if they don't admit it.)

That means that in a closely divided country, Trump is going to have enough support to stay close with Clinton, even if he has alienated key voting groups and even if he isn't able to mobilize some huge new constituency of angry white people. It's why, in the general election horse race polls, he's only trailing Clinton by a few points.

That's the bad news for those who view a Trump presidency with horror. The good news is that a "close" election can actually be less close than it appears.

Consider 2012. Barack Obama beat Mitt Romney by 51-47, around the same size difference as Clinton v. Trump shows now. But Obama won the Electoral College by 332-206. And if you look state by state, it's hard to imagine which of the states Obama won that Trump could move into the Republican column.
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Nevertheless, given all the beating of breasts and tearing of hair on the Republican side, it might be easy to fall into the trap of thinking this will be a blowout election for Democrats, with Clinton winning by a spectacular margin. That won't happen, because partisan attachments have become so firm that they can survive even the candidacy of Donald Trump. Lots of Republicans have misgivings about him, but as the election goes on they'll find ways to convince themselves that he deserves their votes. That will put a floor on his support — probably somewhere around 45 percent — that it will be almost impossible for him to fall below.

Which means that for the next five and a half months until election day, the polls probably won't show Clinton pulling away — and indeed, you may even see a few showing Trump in the lead. But before you panic, remember that it was always going to be this way.

Here's my prediction five and a half months out: Hillary defeats Trump by a slightly larger margin than Obama beat Romney, say 53 to 47 percent. I'll also say the map looks pretty close to the one from 2012, with the possible exception of North Carolina in the blue column. The Democrats will take back the Senate by about a 52-48 margin and gain 15 or so seats in the House, falling well short of a majority.

It will still be gridlock, but gridlock with a Democrat in the White House. Big difference. Supreme Court Justice Anthony Kennedy, for example, will be 80 years old in July. That means a President Clinton could appoint two judges (including Antonin Scalia's replacement), tipping the Court into a 6-3 liberal/conservative split.