State Management Differs With Single Party Control This is problematic because in most states, the minority party has about 40% of voters support.
	p
3. Did the Federal Policy Contribute? The 1987 Communication Industry Fairness Doctrine was eliminated. Radio Stations were no longer required to present contrasting views. Rush Limbaugh, who had popularized conservative talk radio, now had fewer restrictions. Talk Radio and Identity Politics Flourished. Conservative and Liberal Polarization Proliferate 4. Telecommunications Act of 1996 allowed multi-station company ownership and national network developed. As of 2011, Clear Channel Communications  (now  iHeart Media ) owned over 800 US radio stations and   Rush Limbaugh wealth eventually climbed to $400 million. [3]  5. Citizens United v. FEC  Allowed Increased Political Contributions Campaign funding increased and sponsorship diversified,  which supported both intended and unintended Fake News. 6. Sports Trash Talking Went Public Mohamed Ali practically invented this 1960's genre  as a boastfully Cassius Clay. Athlete had been formal, cordial, and boring. Ali changed everything with his elite out-of-ring bantering  which was only rivaled by his in-ring dominance. Larry Bird and others soon followed. 7. Banning Earmarks in 2011 increased polarization as political cooperating to  “bring home the bacon” ended.

Low US Civility Began With the Founders

Federalists painted Jefferson "a crafty, fanatical, “contemptible hypocrite.”
and attacked his moral character, alleging he was an atheist and
a coward during the revolution.

"Callender...a political hack." exposed Hamilton's
affair with married Maria Reynolds
whose husband colluded in the seduction.
Blackmail and rumors of financial improprieties led some lawmakers to investigate but
Congressman William Branch Gail of Virginia eventually excluded that the President fire Hamilton
 but even this leaser resolution did not pass.
 Federalist felt this was a partisan attack.
Hamilton was privately frustrate and felt the House was made-up of ...
"1 bank directors 2. Holders of bank stock 3. Stock jobbers 4. Blind devotees
5. ignorant persons who did not comprehend [the resolutions]
6. Lazy and Good-humored persons...." p286

20th Century Civility Improved

Adolph Ochs bought the NYT in 1898 and responded to his many Yellow Journalism
 competitors with the campaign
"All The News That's Fit To Print."
More congenial media lasted 100 years.

But

Civility Declined in
 in 1987 when Ronald Reagan's FCC eliminated the Fairness Doctrine.
Opposing sides reporting no longer required.
Soon Rush Limbaugh, who had popularized conservative talk radio, had few restrictions.
Talk Radio and Identity Politics Flourished.
 

Trash Talking Went Public in Sports
when Mohamed Ali practically invented this
 early 1960's genre as a boastfully Cassius Clay.
Athlete interviews had been formal, cordial, and boring.
Ali changed everything with his elite out-of-ring talk—
which was rivaled only by his in-ring dominance.
Larry Bird and others soon followed suit.

Banning Earmarks in 2011 increased polarization
as cooperation to “bring home the bacon” ended. source

See Avoiding Effects Of Groupthink

Legality of Behavior Norms Also Up

But

Attitude Toward Abortion Unchanged

It's About Relegion

It's a Personal Liberty and Relegious Liberty

There is a substantial partisan and ideological divide on abortion, with Democrats much more likely than Republicans to say it should be legal in all or most cases. This gap is even larger between liberal Democrats and conservative Republicans: Nearly nine-in-ten liberal Democrats (88%) say abortion should be legal in all or most cases, compared with only about three-in-ten self-described conservatives in the GOP (27%)