Here's how badly the country has fractured over President Trump: He has a near-universal approval among Republicans, while three in four Democrats want him impeached. But it's not like the last few presidents united the country, either.

The back story: It wasn't always this way. Republican Dwight Eisenhower had 49% approval from Democrats during his presidency, as did John F. Kennedy from Republicans. Now, that kind of support for a president from the other party has practically disappeared: Barack Obama had 14% approval from Republicans, and 7% of Democrats approve of Trump.

Expand chart Data: Pew Research Center, Gallup. Reproduced from a Pew Research Center report; Chart: Harry Stevens/Axios

What's behind the trend:

Parties are a lot more ideological, and therefore polarized, than they used to be. Research from the Brookings Institution finds that the gap between average ideological scores for Democrats and Republicans in Congress has grown progressively wider since 1953. The rise of tribalism made the partisan divide less about policy and more about culture. This accelerated under Ronald Reagan, and then took off with cable news in the late 1990s and then digital news a decade later. Those platforms gave Americans ecosystems to have views reinforced and opposing ones pilloried, breeding a non-stop us vs. them feedback loop. Trump has been an exceptional force for polarization, seeking out cultural flashpoints and making criticism of the other side part of the daily routine.

“For almost all of American history, even presidents with strong views have realized that part of their job was to try to unite the country. Starting with Donald Trump’s inaugural address, he suggests an opposite point of view — that uniting the country is not part of his job, and that he thinks a president becomes more powerful if he divides.”

— Presidential historian Michael Beschloss to Axios