These numbers present a problem for gerrymandering critics, particularly those blaming it for the Democrats’ current minority status in Congress. If gerrymandering were significantly advantaging one or the other party, these numbers would not match up.

But this alignment between seats and votes isn’t a new trend. In the three most recent Congresses, the balance of congressional seats between the two parties is nearly identical to the percentage of the vote each party received nationwide in congressional races. In the 2018 midterms, for example, Democrats won 54% of congressional votes nationwide, and ended up with 54% of the seats in the House.

Data I’ve collected for other cycles does show a discrepancy between seats and votes during the Obama years, and it’s probably true that the redistricting process before 2012 cost Democrats a few seats in that decade.

But gerrymandering hasn’t always benefited Republicans: Democrats enjoyed a bigger and more sustained advantage from their district boundaries during the 1970s and 1980s. And if gerrymandering was ever the main cause of Democrats’ seat disadvantage in the House, it’s not today.

Democrats and their allies have been particularly outspoken in their disparagement of gerrymandering, in some cases using some of the same fatalistic language about elections as former President Donald Trump.

For example, one argument during the Obama years was that gerrymandering made it “impossible” for Democrats to win the House. Sometimes the language mirrored Trump’s — that gerrymandering had “rigged” congressional elections in favor of Republicans.

Aside from the well-demonstrated dangers of casting doubt on the nation’s election systems, the evidence simply doesn’t support this doomsday perspective. Democrats do have major problems with geography, but they run much deeper than unfairly drawn lines.

Over the past 30 years, U.S. counties have consistently become less competitive between the parties in presidential elections.

In 1992, the vast majority of counties were won by slim margins, and thus winnable by either party. Only 1 in 3 counties was won by either party by more than 10 percentage points.

But today, the story is the opposite. Nearly 4 out of every 5 counties in 2020 were won decisively – by 10 points or more – by either Joe Biden or Donald Trump.

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