An article from a few years ago is of interest today, with completion of the 2020 US Census.

Analysis indicates partisan gerrymandering has benefited GOP

By DAVID A. LIEB
June 25, 2017

Excerpts:

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 [2016] 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.

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.”

Complete article:

[apnews.com]

Results of the analysis (graphic):

"Measuring the effects of gerrymandering"

[interactives.ap.org]