The mid-decade congressional redistricting war that President Donald Trump triggered is likely to end without any clear partisan benefit for either party. But the cost to the country will be substantial.

Neither party is likely to net a meaningful advantage in the House of Representatives because the competing redistricting frenzies in Republican- and Democrat-controlled states have largely offset each other. But the common effect of both drives will be to further reduce the already shrinking number of “crossover” representatives — Democrats elected to the House from red states and Republicans elected from blue states. That will intensify polarization in Congress. And it will accelerate the partitioning of the country into virtually impregnable, and increasingly hostile, spheres of influence.

Once, it would not have been unusual for a state to have a mix of Democratic and Republican leaders or to vote one way for Congress and the other for president. That was the case for much of the 20th century; even as recently as the late 1980s, Democrats held a majority of both U.S. House and Senate seats in the 38 states that voted consecutively three times for Republican presidents Ronald Reagan and George H.W. Bush. But now, whether a state votes Democratic or Republican for president usually dictates a state’s other major offices, too.

This sorting process reduces the incentive of the president and his legislative allies to consider the interests of the states that voted against him because they have so few local colleagues to worry about protecting. Trump and his aides have pushed this trend to an ominous extreme, routinely portraying the states that he lost as enemy terrain — fit to be subdued, not consulted or courted.

The separation of the country into these spheres of influence is rooted in the shrinking number of “split-ticket” voters who back one side for president and the competing party for other offices. Twenty-five states voted for Trump in each of his three presidential campaigns. The GOP now holds all 50 of those states’ Senate seats and 22 of their 25 governorships. In the 19 states that voted three times against Trump, Democrats similarly hold 37 of those states’ 38 Senate seats and 17 of their 19 governorships. Republicans now control all of the major state-level offices in 21 of the 25 Trump states, just as Democrats do in 17 of the 19 anti-Trump states, according to a new analysis.

The distribution of House seats already follows this general pattern; each party’s ability to win seats on the other side’s terrain has declined since the 1980s. But even the most reliably partisan states have geographic and demographic pockets of support for the other side. Today, Democrats hold 43 of the 185 House seats in the 25 states that voted three times for Trump and Republicans hold 39 of the 185 in the 19 states that voted three times against him.

The redistricting wars will substantially shrink those numbers. Red-state Republicans have redrawn Congressional lines to favor the GOP in about nine Democratic-held seats across Texas, Ohio, North Carolina and Missouri, with Florida poised to eliminate as many as five more later this spring. (A slight offset is that state courts have redrawn the Utah map to create one more Democratic seat.) Blue-state Democrats have responded with efforts to eliminate five Republican seats in California and four in Virginia and are still hoping to gain one more each in New York and Maryland.

Each party may not capture all the seats it expects from redistricting. Trump’s decline with Latinos, for instance, may cost Texas Republicans some of the seats they created. But it would not be surprising if the redistricting war ended with each side losing close to ten seats in the other party’s core states.

And even that may not conclude the re-sorting: If the Supreme Court’s conservative majority further weakens the Voting Rights Act, as it appears poised to do, red states could eliminate up to a dozen more districts now held by non-White Democrats. More states on each side may redraw their lines in 2028, including Colorado.

The result will be to intensify one of the most powerful trends transforming the House. As fewer members represent politically divided constituencies, the differences within each party are diminishing while the disagreements between them are widening.

Each side has recently passed ambitious agendas with far fewer defections from their own members than in the past. But neither side attracted any meaningful support from the other party, which makes those achievements more vulnerable to reversal each time control of the House and Senate changes hands. For example, Republicans in 2025 used party-line votes to erase the clean energy incentives and health-care expansions Democrats approved on party-line votes under Biden.

Although Republicans and Democrats no longer negotiate very much with each other, each side is still compelled to consider the interests of the “crossover members” hailing from states controlled by the other party. Those members usually have a moderating effect on legislation, making it more balanced and durable.

But that pressure to bargain internally will dwindle as the redistricting war continues. Phil Schiliro, the White House legislative affairs director for former President Barack Obama, told me that while less internal negotiation will “make it easier” to pass bills, it will further diminish the incentive to craft legislation with support broad enough to endure. Whiplash-inducing “volatility in public policy” will become more routine, he warns, with severe “negative consequences for the country.”

Doug Heye, a former House GOP leadership aide, points to another way the redistricting arms race will intensify polarization. “We’ve made even more seats where your first priority is your primary, not your general election,” Heye says.

The greatest risk in this partitioning extends far beyond congressional polarization. When the country is so divided between distinct spheres of political influence, it is easier for leaders and ordinary Americans alike to view the other bloc as adversaries, not neighbors. Trump’s pile-driver presidency is already imposing the greatest strain on the nation’s fundamental cohesion since the Civil War. The redistricting frenzy is tugging further at the fraying threads that hold together America.

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This column reflects the personal views of the author and does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Ronald Brownstein is a Bloomberg Opinion columnist covering politics and policy. He is a CNN analyst and the author or editor of seven books.

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