Lee Drutman for 538:

Competitive congressional districts have been steadily disappearing for decades. In the current redistricting cycle, six highly competitive districts in the House of Representatives were drawn out of existence. The Cook Political Report estimates that less than 8 percent of congressional districts will be competitive come November.

This is a problem. It’s not because competitive districts are a powerfully moderating force on our democracy — instead, the decline of competitive districts is a problem that reflects deeper causes of partisan polarization and leaves the overwhelming majority of Americans in places where their votes don’t matter, and where parties and candidates don’t need to work for anybody’s votes.

Governing in America requires compromise. But when over 90 percent of congressional districts lean toward one of the two major parties, that means most representatives have little incentive to compromise. In fact, representatives increasingly face strong pressures to be very partisan, which has made governing very difficult.

But perhaps more importantly, when there isn’t competition, citizens and parties have little reason to show up and vote. Instead it becomes the highly organized donors and activists who are engaged, while the rest of the district is ignored. It’s true that competitive districts might not produce especially moderate candidates, but they are important when it comes to engaging and informing citizens. And this participation has valuable spillover effects for communities, well beyond our elections. …