Michael Barone explains for the Washington Examiner why gerrymandering does not have as much impact as conventional wisdom suggests.

Does gerrymandering matter? Not as much as you might think. You’re sure to be wrong if you take at face value the rhetoric of liberals who seem to place most of the blame for Republican majorities in the House of Representatives on partisan map-making.

I have argued repeatedly — in December 2017, September 2017, July 2015, October 2014, September 2014, January 2014, and February 2013, that redistricting is less important in securing Republican congressional and legislative majorities than demographic clustering — the fact that Democratic voters are increasingly concentrated in black, Hispanic, gentry liberal and university areas.

That’s because Democrats’ huge majorities in districts dominated by such voters do nothing to elect Democrats in the remaining districts. A party with clustered constituencies is inevitably disadvantaged by a system of equal-population legislative districts. That conclusion is confirmed by the research of political scientists Jowei Chen (University of Michigan) and Jonathan Rodden (Stanford), as reported in the New York Times in 2014, and it was confirmed once again last week by the work of David Wasserman and three colleagues at FiveThirtyEight in their Atlas of Redistricting. …

… Why do Republicans tend to have an advantage in redistricting, and why do partisan Democratic districting plans tend to produce less compact and aesthetically pleasing district boundaries? “First,” Wasserman writes, “more than in past decades, Democratic voters are inefficiently clustered in big cities and college towns.” Bill Clinton’s 49 percent 1996 coalition was spread more evenly around the country than Barack Obama’s 51 percent 2012 coalition.

“Second, the Voting Rights Act limits the extent to which Democrats can spread their voters across many districts, because it provides safeguards against diluting majority-minority districts.” The courts have been finagling about the rules and chipping away at the long prevailing interpretation of the Voting Rights Act that required maximizing the number of majority-minority districts; but this is still a handicap for Democrats.