How Gerrymandering Works

Gerrymandering exists in part because both state legislative and congressional districts are redrawn every so often so they have a uniform population size, and everyone's vote counts equally. Article 1, Section 2 of the U.S. Constitution, for example, calls for congressional representation to be apportioned according to population every 10 years, according to the results of the U.S. Census.

At least, that's how it's supposed to work.

The problem is that in most states, the process is run by the partisan politicians themselves. And they often can't resist the temptation to draw districts in ways that's advantageous to their parties. The idea is to make one party waste votes — i.e., cast them in a way that doesn't help them to win a majority of representatives, or even the amount that they should be allotted according to their percentage of the electorate [source: Cameron].

Imagine, for purposes of illustration, that a state has only 500 voters — 200 from the Yellow Party and 300 from the Orange Party. If the state is divided into five districts of 100 voters each, you'd think that would mean that the Orange Party would get be able to win three of the five seats. But if the Yellow Party has been in power for a while, it can draw districts that minimize the Orange Party's larger voting base.

One way would be to divide the state into oddly shaped districts, two of which are almost completely Orange voters. The other three would have 60 percent Yellow voters and 40 percent Orange ones. The result is that many of the Orange votes end up being wasted. The Yellow Party would waste a few votes, too, but it still would end up electing more legislators [sources: Cameron, Petry].

University of Chicago law professor Nicholas Stephanopoulos, and Eric McGhee, a research fellow at the Public Policy Institute of California, call the number of wasted votes the efficiency gap [source: Petry].

There are two main gerrymandering techniques. One is cracking, the practice of scattering an opposition party's political supporters across multiple districts, so that they don't form a majority in any of them. The other is packing, in which those partisans are jammed into a few districts (this was our Yellow and Orange Party illustration). Even though the opposition party wins overwhelmingly there, it still loses the majority of districts [source: Treleven].

Gerrymandering is a sneaky trick with a long and illustrious history, dating back to the beginnings of the nation. In 1788, shortly after Virginia ratified the U.S. Constitution, founding father and former-governor Patrick Henry convinced state legislators to redraw the fifth congressional district in order to force his political foe James Madison to run against James Monroe, whom Henry figured would win. But Henry's scheme backfired when Madison came out on top anyway [source: Barasch].

It got only worse from there. In 1812, Massachusetts Gov. Elbridge Gerry did his part to help his party, the Democratic-Republicans, hang on to the state legislature. He signed into law a bill that created a strangely shaped district designed to make it tough for candidates of the rival Federalist Party to win. On the map, the district looked a bit like a salamander, and a newspaper cartoonist labeled it the "Gerry-mander." The name stuck [sources: Donnelly, Draper, Barasch].

Gerrymandering grew so common and blatant that Congress tried to control it with the Apportionment Act of 1842, which required, among other things, that congressional districts be drawn to be contiguous and compact as possible. But the temptation to use the map to political advantage was too tempting. In the 1880s, the Republican-controlled Congress even engaged in a sort of gerrymandering on a grand scale, carving out two separate states — North and South Dakota — in order to gain more seats in the U.S. Senate [source: Barasch].

Gerrymandering was so effective that both Republicans and Democrats engaged in it. In the 1950s, for example, Democratic legislators in Texas drew what political writer Robert Draper calls "pronouncedly racist maps" in order to deprive African-Americans and Hispanics of their right to representation.

Gerrymandering also flourished because for most of the nation's history, the federal courts didn't take much interest in it, deeming it a political rather than a constitutional problem, which voters could remedy simply by throwing out the party in power. (That view had an inherent flaw, since gerrymandering was intended to keep voters from doing that.) Finally, in 1962, the U.S. Supreme Court ruled in Baker v. Carr that Constitutional challenges could be mounted to redistricting plans [sources: Whitaker, Utm.edu].

Additionally, the passage of the Voting Rights Act of 1965 set up rules to ensure that racial and ethnic minority voters weren't spread out in a way that diluted their political power [source: Barasch]. But efforts to draw maps that gave minorities more political influence sometimes led to even stranger configurations. In the 1990s, for example, North Carolina legislators drew up a congressional district that snaked narrowly across the state in order to pick up pockets of African-American voters [source: Wattson].

That map was thrown out in 1996 when the Supreme Court ruled that even districts drawn to be fair to minority voters should maintain "compactness, contiguity and respect for political subdivisions" [source: Draper].

But up until now, the Supreme Court has yet to agree upon a legal standard that would make it clear when redistricting maps are unconstitutional. The Wisconsin case could change that [source: Fritze].

Because of its long history, gerrymandering conjures up an image of old-school political bosses gathering in smoke-filled rooms to twist arms and dicker over who gets which precincts, as they draw the borders of districts on paper.

But those days are long gone. Redistricting has become a technologically complex affair, shaped by political consultants who roam the country and guide state legislators in redrawing political maps with the help of sophisticated software that processes population data to draw and tinker with hypothetical maps [source: Draper].

To critics of gerrymandering, the Wisconsin state legislative map being reviewed by the U.S. Supreme Court in Gill v. Whitford is a prime example of how technology has made things even worse. As University of Wisconsin mathematics professor Jordan Ellenberg detailed in a New York Times opinion piece, after Republicans gained control of the Wisconsin statehouse in the 2010 election, they used computer algorithms to test how various possible legislative maps would perform in future election scenarios. The result, according to Ellenberg, was a map "precisely engineered to assure Republican control in all but the most extreme circumstances."

The Wisconsin map is designed so ingeniously that if the proportion of Democratic votes rises above 50 to 52 percent, it actually becomes even more skewed toward the Republicans [source: Hershlag, Ravier and Mattingly]. In order to wrest away control of the Assembly, Democrats would have to defeat Republicans at the polls by a statewide margin of eight to 10 points — hardly doable in state split evenly between the two major parties [source: Ellenberg].

But high-powered computing and intricate math work both ways. While political map-makers can use those tools to create maps with the maximum amount of unfairness, it's also possible for political scientists and mathematicians to use the same tools to show that a gerrymandered map is a true outlier — that is, one that's so far outside the ordinary, it was obviously drawn up just to create a partisan advantage.

To a degree, whether gerrymandering is bad for democracy probably depends upon if you're in the party that's clinging to power, or the opposition that is struggling to wrest it away.

But it's hard to argue that gerrymandering hasn't distorted the political system and sometimes led to political representation that doesn't really reflect the voters' views. North Carolina, for example, has evolved over the years from a deep red state into a swing state that Barack Obama won in 2008, and Mitt Romney and Donald J. Trump only won narrowly in the two elections that followed. But you wouldn't know that from the state's Congressional delegation. In 2012, for example, 51 percent of North Carolina voters cast ballots for Democratic Congressional candidates. Yet because of gerrymandering, Republicans won nine of the state's 13 seats [source: Savage].

But even some politicians whose parties have benefited from gerrymandering have come to recognize that it undermines the integrity of the American political process.

In Maryland, for example, former Gov. Martin O'Malley has admitted that when he presided over the re-drawing of the state's congressional districts in the early 2010s, he was convinced that Democrats should use their power to pass a map that gave them an advantage in winning elections. Map-drawing tricks enabled the Democrats to oust a longtime Republican incumbent, Rep. Roscoe G. Bartlett, in a 2012 race [source: Hicks, Savage].

Maryland is a deep blue state — Hillary Clinton won 60 percent of the vote in the 2016 presidential election, for example — and the state's voters actually approved the Democratic-drawn map in a 2012 referendum. Nevertheless, since then, O'Malley — who left office in 2015 and mounted an unsuccessful campaign for president in 2016 — has changed his mind. In a 2017 speech at Boston College, he called for an end to the gerrymandering of congressional districts, saying that it's led to a political climate in which divisiveness and extremism have paralyzed government.

"Gone from the Congress of today are the Rockefeller Republicans and the Blue Dog Democrats," O'Malley explained, citing two groups of moderates who've become virtually extinct. "Instead, we've fostered a system that drives our representatives apart, a system that has wiped out diversity of opinions."

Advocates of reforming the political process say that there's a way to eliminate gerrymandering and make elections fairer. They'd like to take control of the legislative and congressional redistricting process away from elected politicians whose parties stand to benefit from drawing skewed maps. Instead, they want states to turn redistricting over to independent, non-partisan commissions.

It's an idea that sounds promising, at least in theory. But so far, only six states — California, Arizona, Washington, Idaho, New Jersey and Hawaii —give complete control over congressional redistricting to commissions, whose maps don't need final approval from state legislators or governors. And as Vox journalist Andrew Prokop noted in a recent article, simply setting up a commission doesn't keep politics out of the process, because the political leaders get to decide who's on the commission, and seats are reserved for Democratic and Republican appointees — though some states also reserve seats for independents or non-partisan commissioners.

So far, there's mixed evidence on whether commissions can open up the political process and reduce unfairness. In California, for example, a referendum turned congressional redistricting over to a commission in 2010. But since then there hasn't been that much change in the partisan make up of California's congressional delegation. In 2016, for example, all the state's 53 congressional districts were won by the party that previously controlled them. But the new map has led to more races being competitive. One example: Longtime Republican incumbent. Rep. Darrell Issa, who won 63 percent of the vote in 2010, squeaked by in 2016 with a margin of less than 1 percent [source: Blake].

But Americans also can look to the north for an example of how commissions can make politics fairer. In 1964, Canada — where extreme gerrymandering once was common — passed a law that set up a three-member commission to draw up electoral districts for each province, with a superior court judge — a non-elected official — as the chairperson. The other two members are either political science professors affiliated with universities, or else retired government officials. Members of Parliament are allowed to raise concerns about the draft versions of the maps, but the commission's decision is final. The population of each electoral district must correspond with the province's electoral quota as much as possible [source: Courtney].

As legal scholar Charles Paul Hoffman has written in the Manitoba Law Journal: "The commissions have been largely successful since their implementation." As a result, Canada has morphed into a country where people might still complain about their elected officials, but the make up of districts is no longer a source of bitter controversy.