Political polarization in the U.S. is intense and damaging. The Supreme Court could take a small step to mitigate it by limiting partisan gerrymandering.


Curtailing patently political drawing of districts for the U.S. House of Representatives and state legislatures wouldn’t markedly change the partisan composition of either. Under a fair redistricting plan that isn’t designed to help one party at the expense of the other, Republicans, who controlled most of the power after the 2010 census, might lose up to 10 House seats. They’d still retain a solid majority. (When Democrats control the levers of power, they act the same way.)


But many district lines are contorted to create safe seats in a general election, usually for incumbents. If the job of drawing them were done by nonpartisan commissions instead of party activists, as now happens in four states, dozens more seats might be competitive. Competition makes politicians reach out to uncommitted voters instead of playing to their core base.


The Supreme Courts tends to avoid ruling on redistricting fights. But it is now considering a challenge to an egregiously partisan Wisconsin redistricting plan. Skeptics wonder how a workable rule for what’s acceptable could be fashioned.


The effect of gerrymandering on the U.S. House after the 2010 census is illustrated by looking at Florida, Ohio, North Carolina, Pennsylvania and Michigan. Politically, these are the big five swing, or purple, states. They all voted for Barack Obama in 2008 and all but North Carolina did the same thing four years later. They all went for Trump last year.


In statewide elections where there are no district lines to manipulate, voters in those states have elected three Republican governors and two Democratic ones. The states’ 10 senators divide half-and-half.


Yet of the 87 current House members from these five states, 60 are Republicans. There are more than a few rigid ideologues on both sides who have little interest in seeking common ground.


That’s part of the case against partisan gerrymandering made by 34 present and former House members from both parties who filed an amicus brief urging the High Court to overturn Wisconsin’s redistricting plan.


“Members are less inclined to talk and cooperate, much less compromise,” wrote Rep. Earl Blumenauer, an Oregon Democrat, and Jim Leach, a former Republican congressman from Iowa, in a 2003 New York Times opinion article cited in the brief. “The legislative agenda is shaped more to energize the political base than to advance the common good.”


Well over 90 percent of House members are routinely re-elected. Because most hail from districts dominated by one party, they don’t worry about their prospects in the general election. The only threat to their re-election comes if they’re challenged in party primaries, so they try to protect their right or left flank.


There always will and should be issues that sharply divide the parties: taxes, health care, entitlements, defense spending and now race.


But there should be room for some accommodation, as there was even when there were deeper social schisms; think of the eras of the Vietnam War, the civil rights struggles and the New Deal. Yet polarization seems more damaging today.


There are numerous other factors: the campaign finance system, permanent campaigning, the rise of social media and hyperpartisan media. Population patterns also play a big role, with like-minded people tending to cluster together in ways that favor one-party congressional and legislative districts.


No Supreme Court redistricting decision can suddenly create the “more perfect union” envisioned in the preamble to the U.S. Constitution. But if the court ducks the gerrymandering issue, the system — and the public cynicism it helps create — will only get worse.


Albert R. Hunt is a Bloomberg View columnist. He was the executive editor of Bloomberg News, before which he was a reporter, bureau chief and executive Washington editor at the Wall Street Journal. Readers may email him at ahunt1@bloomberg.net.