There's also the gerrymandering, which is likely to get worse:
Ari Berman @AriBerman
Overlooked news: GOP gained 22 extra seats in House through partisan gerrymandering according to @AP analysis t.co/hvO5iPKZ5I?amp=1
Less attention was paid to manipulation that occurred not during the presidential race, but before it — in the drawing of lines for hundreds of U.S. and state legislative seats. The result, according to an Associated Press analysis: Republicans had a real advantage.
The AP scrutinized the outcomes of all 435 U.S. House races and about 4,700 state House and Assembly seats up for election last year using a new statistical method of calculating partisan advantage. It's designed to detect cases in which one party may have won, widened or retained its grip on power through political gerrymandering.
The analysis found four times as many states with Republican-skewed state House or Assembly districts than Democratic ones. Among the two dozen most populated states that determine the vast majority of Congress, there were nearly three times as many with Republican-tilted U.S. House districts.
Traditional battlegrounds such as Michigan, North Carolina, Pennsylvania, Wisconsin, Florida and Virginia were among those with significant Republican advantages in their U.S. or state House races. All had districts drawn by Republicans after the last Census in 2010.
The AP analysis also found that Republicans won as many as 22 additional U.S. House seats over what would have been expected based on the average vote share in congressional districts across the country. That helped provide the GOP with a comfortable majority over Democrats instead of a narrow one.
"The outcome was already cooked in, if you will, because of the way the districts were drawn," said John McGlennon, a longtime professor of government and public policy at the College of William & Mary in Virginia who ran unsuccessfully for Congress as a Democrat in the 1980s.
A separate statistical analysis conducted for AP by the Princeton University Gerrymandering Project found that the extreme Republican advantages in some states were no fluke. The Republican edge in Michigan's state House districts had only a 1-in-16,000 probability of occurring by chance; in Wisconsin's Assembly districts, there was a mere 1-in-60,000 likelihood of it happening randomly, the analysis found.
The AP's findings are similar to recent ones from the Brennan Center for Justice at the New York University School of Law, which used three statistical tests to analyze the 2012-2016 congressional elections. Its report found a persistent Republican advantage and "clear evidence that aggressive gerrymandering is distorting the nation's congressional maps," posing a "threat to democracy." The Brennan Center did not analyze state legislative elections.
There's more in the article but it's worth a read