Call it MAG: Mutually Assured Gerrymandering. First Texas, under pressure from the White House and Justice Department, began redrawing its district maps in the middle of the decade — although the process is normally undertaken after a new census. Now several blue states have said they may attempt to follow suit, which would mean warping their own districts to further boost the Democrats.

Gerrymandering has long been a problem, but this is a new level of insanity that should spur urgent demands for reform. Addressing the problem requires states or Congress to step up and produce fair maps, judged by objective measures. My research suggests one way to do so, based on how far a map departs from perfect compactness.

Redistricting isn’t my usual beat. I’m an economist who dissects race and inequality to design fixes for stubborn social ills — and a venture capitalist who then backs the market solutions those findings inspire, instead of letting them languish in obscure academic journals or well-meaning nonprofits.

Back in 2004, soon after earning my Ph.D., I found myself in the Harvard Society of Fellows chatting with a Supreme Court justice. I asked what single problem math or economics could solve for the Court. The answer was instantaneous: Give us an objective yardstick for political maps. (Others have tried their own remedies).

After months huddled around a whiteboard with a sharp graduate student, Richard Holden, fueled by too much bad Harvard Square coffee, we created a measure we call the “Relative Proximity Index.”

Picture every voter as a dot on the state map. First, we pin down the geometric minimum — the most compact way to bundle those dots inside the state’s jagged borders into its exact number of congressional districts, each with equal population, whether that means wrapping around Florida’s panhandle or hugging Georgia’s slanted shoulder. Then we compare the map the legislature actually draws to that floor. The ratio is the Relative Proximity Index. An R.P.I. of 1 means you’ve hit the geometric ideal; an R.P.I. of 3 means voters within a district would live — on average — three times farther apart than necessary.

Since compactness isn’t the only legitimate redistricting criterion, we shouldn’t expect maps to hit 1.0. Lawmakers need room to respect county and city lines, comply with the Voting Rights Act and keep real neighborhoods intact. But compactness should be the starting point because it is neutral, measurable and easy to audit.

It subsumes contiguity (tight districts are, by construction, connected), discourages gratuitous splits of counties and cities, and helps protect genuine communities by forcing mapmakers to justify every detour. Start with the tightest lawful plan; if you deviate, say why, in public. As a rule: the bigger the R.P.I., the heavier the mapmaker’s thumb on the scale.

Our 50-state census of the 106th Congress — from 1999 through 2001 — turned up five of the least-compact maps: Tennessee (R.P.I. = 2.91), New Jersey (2.27), Texas (1.90), Massachusetts (1.87), and New York (1.83). To see what a strict maximal compactness rule would change, we looked at seat-vote curves — a standard political science tool showing how a party’s share of the statewide vote translates into seats — comparing current maps with compact redraws in California, New York, Pennsylvania and Texas.

Two parts of the curve matter: Bias is the built-in tilt at a 50—50 vote. If each party gets half the votes, but one still wins 55 percent of the seats, that’s a +5-point bias for that party. Responsiveness is the slope — the number of seats that change hands when the statewide vote moves by one percentage point. High responsiveness means small shifts in public opinion cause more seats to flip; low responsiveness means the seat count hardly budges.

The results were striking: under maximally compact maps, responsiveness jumped in all four states, while bias stayed about the same. In other words, compactness doesn’t change which party starts with the advantage — it changes how many races are actually competitive, and how much voters’ choices can move the scoreboard. The empirical data show compactness is not cosmetic; it’s what turns a fixed match into a fair fight.

In my view, the R.P.I. is the most attractive measure of gerrymandering. While it focuses on compactness to the exclusion of other criteria, it is a simple, easy-to-understand approach. It does not require an opaque computer algorithm to draw thousands of maps for comparison, and it does not rely on an assumption that a fair map will produce proportional representation (which may not be true, depending on how the parties’ constituencies are distributed geographically).

The Supreme Court’s 2019 decision in Rucho v. Common Cause closed the federal courthouse door to partisan-gerrymandering claims. It didn’t bless the practice; it handed the ball to the states and to Congress.

What can states do, then, that’s more productive than tit-for-tat gerrymandering? They can act now.

First, write a compactness standard into law: Any map with an R.P.I. above 1.5 is presumptively illegal unless lawmakers can show, district by district, a compelling “community of interest” reason to stray. In our data, 31 of 50 states would pass this test. And under the Elections Clause, Congress can set baseline transparency and compactness guardrails for U.S. House maps — no need to draw a single line itself. Think of it as a speed limit. Drive over it, and you’d better have flashing lights.

Second, outsource the cartography. Hand the pencils to an independent commission that agrees, from day one, to publish every line of code it uses. If a teenager in Lubbock, Texas, can download the algorithm and draw a tighter, population-balanced map, the commission should explain why its version is better. Sunshine is a marvelous disinfectant.

Finally, require an automatic audit. Any middecade tweak triggers an R.P.I. check by a three-judge panel. No more charter-bus theatrics or quorum-busting flights; the math goes to court and the court rules — quickly.

Even with a clean mathematical yardstick, I can already hear the usual grumbles. First, the rural plea: “Odd-shaped districts are the only way to keep West Texas on the map.” Not so. Because the R.P.I. is population-weighted, the Panhandle, the Permian, and every dusty county in between sail comfortably under the cap. The map contortions we flag aren’t out on the sagebrush; they’re in Houston’s sprawl.

Next, the minority alarm: “Compactness will wipe out Black and Latino representation.” The opposite is true. A strict cap forces those drawing the maps to justify every split, making racial gerrymandering harder, not easier.

Finally, the fatalist shrug: “Partisan gerrymandering is as old as Elbridge Gerry — live with it.” Insider trading is just as old, yet we still police Wall Street to make finance fairer. Elections are no different: let politicians torque the lines, and everyone sees the thumb on the scale. Democracy ends up paying the bid-ask spread.

This fight hits home for me. I moved to Texas at age 5 and stayed through college. We pride ourselves on straight shooting. But the facts — who lives where — don’t match the tall tales coming out of Austin. One district hugs the Rio Grande for well over 500 miles, from San Antonio’s outskirts almost to El Paso. That’s not state pride; it’s sleight of hand. “Don’t mess with Texas”? Fine. Stop messing with Texas , and with the blue states preparing to respond in kind.

Pass an R.P.I. cap, post the code on GitHub and let the best maps win. That’s a Texas two-step even Democrats can dance to.

Roland Fryer is a professor of economics at Harvard University.

Source images by Tanja Ivanova and mikroman6/Getty Images

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