How Maps Reshape American Politics

By Nick Corasaniti, Reid J. Epstein, Taylor Johnston, Rebecca Lieberman and Eden WeingartNov. 7, 2021

We answer your most pressing questions about redistricting and gerrymandering.

Democrats in Illinois have drawn a new congressional map that could give them 14 of the state’s 17 House seats.

Here’s how they drew the 17th District.

Why is it shaped like that? To pack in as many Democrats as possible, by including liberal cities and bypassing conservative rural areas.

This is the little-understood art of redistricting. It’s what determines how much your vote really counts.

1.So, congressional districts and state districts are being redrawn. Who cares?

You should! Changes to district maps can alter the balance of power in Congress and in the states. The new maps last for a decade. They can give one party an unfair advantage — in each state, and nationwide. And redistricting contributes to political polarization by making elections less competitive.

This year, with an extremely slim Democratic margin in the House of Representatives, simply redrawing maps in a few key states could determine control of Congress in 2022.

House of Representatives party breakdown

218 for control

Democrats

Republicans

213

221

Democrats

Republicans

221

213

Source: U.S. House of Representatives Press Gallery

2.OK, you have my attention. So what is redistricting?

It’s the redrawing of the boundaries of congressional and state legislative districts. It happens every 10 years, after the census, to reflect the changes in population. And data from the 2020 census, delayed by the pandemic, was just released in August.

Over time, districts gain or lose population. That gives a voter in a district with a bigger population less of a say than a voter in a sparsely populated district. New maps are drawn to keep the population in each congressional district roughly even.

3.That doesn’t sound so bad.

Nope, not in theory. But it is an intensely political process, and can alter the fairness of elections before any votes are cast. District lines can be redrawn to favor one party or the other, to protect incumbent elected officials, or to help — or harm — a specific demographic group.

Abuse of the system is responsible for a host of political ills, especially polarization.

Understanding redistricting is essential to understanding just how much a vote actually counts.

4.Got it. So how does this work?

Redistricting starts with the census, the federal government’s comprehensive count of the country’s population and its changing demographics.

The census dictates how many seats in Congress each state will get, which is why some states gain or lose seats in the House of Representatives every 10 years. That reshuffling is known as reapportionment.

Mapmakers then work to ensure that a state’s congressional districts all have roughly the same number of residents, to ensure equal representation in the House of Representatives. They also do the same for the districts of state legislators.

That requires moving the borders of districts — or adding new districts and subtracting old ones — to achieve population parity.

Congressional seat changes by state after the 2020 census

Gaining seats

Losing seats

Gaining seats

Losing seats

Gaining seats

Losing seats

5.Is that it?

Not quite. While the basic mission is simple — ensuring equitable representation — there are some rules of the road. The Voting Rights Act of 1965 forbids “dilution” of the votes of people of color: Maps may not be drawn to limit such voters’ ability to elect their own representatives.

Many states have other criteria: keeping districts geographically contiguous and compact, ensuring that elections will be competitive, or safeguarding partisan “fairness” — so districts reflect statewide voting trends rather than giving one political party an unearned advantage.

Voting Rights Act of 1965

The landmark Voting Rights Act prohibited racial discrimination in voting and ushered in a host of new protections. Racial gerrymandering was forbidden, and states with a history of discrimination at the polls had to get clearance from the Justice Department before changing voting laws or drawing new maps. By the end of 1965, 250,000 new Black voters had registered.

6.Who draws the new maps?

Each state has its own process. Eleven states leave the mapmaking to an outside panel. But most — 39 states — have state lawmakers draw the new maps for Congress. (Six states will have only one House seat, so they have no congressional districts to draw.)

Control of redistricting

Democrats

Republicans

Bipartisan or split

Panel

Single district

Democrats

Republicans

Bipartisan or split

Panel

Single district

Democrats

Republicans

Bipartisan or split

Panel

Single district

7.Wait, state legislators can draw their own districts? Won’t they be biased?

Yes, and this is one way that redistricting becomes so politicized. Partisan mapmakers often move district lines — subtly or egregiously — to cluster voters in a way that advances a political goal, like helping their party or bolstering an incumbent’s chances of re-election.

That allows a political party to choose its voters, rather than the voters choosing their representatives. And it often leaves a legislature with a partisan slant that doesn’t represent the statewide political balance.

Take Wisconsin: In 2018, former Gov. Scott Walker, a Republican, lost by less than 30,000 votes statewide, a margin of just one percentage point. But Republicans still won 63 of the 99 State Assembly districts.

That’s a sign of a highly gerrymandered map.

Wisconsin’s 2018 election

Popular Vote

49.6%

48.5%

Assembly Districts

Popular Vote

49.6%

48.5%

Assembly Districts

Sources: Ballotpedia; New York Times 2018 election results

8.Gerry-what?

Gerrymandered. It’s a word with a funny back story. We’ll get to that later. But in simple terms, it refers to the intentional distortion of a map of political districts to give one party an advantage.

9.How can one side get such an edge from a map?

While all districts must have roughly the same population, mapmakers can make subjective decisions on how to draw the boundaries, and how to group voters in a district, to create a partisan tilt. Let’s look at a simple illustration.

Click through to see how it works.

Suppose a state has 25 voters who live in a perfect grid. Sixty percent of them belong to the Blue party, and 40 percent to the Red party.

Say the state has five House seats. We need districts roughly the same size. We can draw them to fairly reflect the population: Blue gets three seats, Red gets two seats.

But what if we want to give Blue the advantage? If we draw the districts like this, Blue holds a majority in all five districts.

Now, let’s draw a map that helps the Red party. We’ll need to get creative, since it’s in the minority. But check out what happens if we draw the districts this way.

There are many ways to slice and dice districts, but two methods of gerrymandering are used most often: “cracking” and “packing.”

10.That sounds catchy. What’s ‘cracking’?

Cracking is when mapmakers break up a cluster of a certain type of voters — people from a specific demographic group, or simply affiliated with the opposing party — and spread them among several districts, diluting their vote rather than allowing them to exert a larger influence in fewer districts or even a single district.

This is a common tactic in densely populated areas, and is often described as “pizza slicing,” as if the city were the center of a pizza cut up narrowly at the urban core along lines radiating outward.

Click through to see how cracking works.

Let’s consider a slightly bigger state, with 50 people, but still just five districts. Say 64 percent of the state votes Red and 36 percent votes Blue.

But the Red party controls the redistricting process, and wants to gain an advantage.

By “cracking” the Blue voters, mapmakers could break up the Blue vote so that Red ends up with a majority in all five districts.

11.Wow. And what’s ‘packing’?

Packing is when maps are drawn to cram the members of a demographic group, like Black voters, or voters in the opposing political party, into one district or as few districts as possible. That leaves their numbers in the other districts too scant to win elections. This is how many states, primarily in the South, sought to limit the influence of Black voters over the decades before the introduction of the Voting Rights Act.

Click through to see how packing works.

This time, let’s say the Blue party enjoys 64 percent support statewide, and the Red party 36 percent.

The Blue party controls redistricting and does not want to worry about competitive elections.

Rather than cracking Red voters, the Blue party packs as many Red voters as it can into one district. The Blue party can carve out four very safe seats, leaving the Red party with one.

12.Wow! Can you give some real-life examples of how this works?

Absolutely. Perhaps no city in America was more cracked than Austin, Tex., the only U.S. city of less than a million residents that was divided among six congressional districts. In the 2020 election, President Biden won Travis County, which includes Austin, by 45 percentage points. But five of Austin’s six congressional seats are occupied by Republicans.

Toggle between the two maps to see how Austin was cracked.

2020 Vote Share

2011 District Map

This is the area around Austin represented by how people voted in the 2020 election. You’ll see a big area of blue that fades into some smaller pockets and expanses of red in the rural areas.

2020 presidential vote margin by precinct

Austin

+30

Biden

+15

Biden

+15

Trump

+30

Trump

2020 presidential vote margin

by precinct

Austin

+30

Biden

+15

Biden

+15

Trump

+30

Trump

In the 2020 election, Democratic votes in Austin were cracked into multiple districts reaching into conservative areas. There are about 435,000 Democratic voters in Travis County, and only about 160,000 Republicans — but just one Democratic representative.

Current party representation of congressional districts

Austin

Republican

Democratic

Current party representation of

congressional districts

Austin

Democratic

Republican

13.Got it. But where’s a good example of packing?

Well, we can actually turn right back to Austin. After decades of cracking Austin apart, the city’s Democratic vote was growing too large to be diluted by surrounding rural areas. Those Republican seats threatened to tip Democratic. So Republican legislators changed their strategy.

Toggle between the two maps to see how Austin was packed.

2020 Vote Share

2021 District Map

Republicans drew a new district (37) that was 75 percent Democratic, segregating Democratic votes and preserving the Republican tilt of the surrounding districts. Simply put, they conceded one seat to save the others.

2020 presidential vote margin by precinct

(new)

Austin

+30

Biden

+15

Biden

+15

Trump

+30

Trump

2020 presidential vote margin

by precinct

(new)

Austin

+30

Biden

+15

Biden

+15

Trump

+30

Trump

This is how packing works. Democratic voters are packed into one district (37) — a new island of blue among districts that are once more solidly Republican.

Expected party representation of congressional districts

(new)

Austin

Republican

Democratic

Expected party representation of

congressional districts

(new)

Austin

Democratic

Republican

14.All right. Cracking and packing — is that it?

No, there are other tricks.

Take Oregon’s new congressional maps. The state gained a seat in reapportionment, and the Democrats who control the State Legislature decided to grab it. They broke up heavily Democratic Portland — carved up into three districts since 2011 — into four districts, forking outward into rural areas in the state. That should give the party a 5-to-1 advantage in the congressional delegation.

Toggle between the two maps to see how Oregon added a Democratic seat.

2011 Oregon Map

2021 Oregon Map

In redistricting after the 2010 census, the Oregon Legislature divided metropolitan Portland into three of the state’s five congressional districts (1,3,5). Everything east of the Cascade Mountains went into a solidly Republican district (2), while southwestern Oregon was a Democratic-leaning competitive district.

Democratic

Republican

Democratic

Sources: New York Times 2020 election results; Princeton Gerrymandering Project

This year, Oregon Democrats pressed their advantage. They split Portland into four districts (1,3,5,6), including one reaching across the Cascades to Bend (5), a Democratic city. The southwestern district (4) added more Democratic areas, putting it out of reach for Republicans.

Republican

Democratic

Republican

Sources: New York Times 2020 election results; Princeton Gerrymandering Project

15.Well, this sounds bad. What does it do to the political process?

Simply put, it makes elections less fair. The mapmakers’ party can seize such an advantage that November elections become foregone conclusions. Take North Carolina in 2012, after the state enacted an aggressively gerrymandered map. Democrats won 50.6 percent of the statewide congressional vote, but only four out of 13 House seats. (Federal courts eventually forced the state to redraw the map — twice.)

North Carolina 2012 Election

Popular Vote

50.6%

48.4%

Congressional Seats

Popular Vote

48.4%

50.6%

Congressional Seats

Source: New York Times 2012 election results

This played out across the country a decade ago, after Republicans took over control of dozens of statehouses in the 2010 midterm elections and, in that year’s redistricting cycle, were able to draw many more maps than Democrats.

The result? In 2012, as President Barack Obama sailed to re-election, Democrats received 1.4 million more votes than Republicans for the House of Representatives. But Republicans retained control of the House by a wide margin, 234 seats to 201.

16.This sounds as if it should be illegal. Is it?

Yes and no. In 2019, the Supreme Court ruled in Rucho v. Common Cause that the federal courts have no role to play in blocking partisan gerrymanders.

However, the court left intact parts of the Voting Rights Act that prohibit racial or ethnic gerrymandering. Districts where people of color are in the majority are often referred to as V.R.A. districts, and breaking them up is almost certain to draw a lawsuit.

States have often been forced to redraw maps found to have violated the Voting Rights Act or the equal protection clause of the Constitution. Pennsylvania had to redraw its congressional maps in 2018; Texas has had to redraw at least some of its maps every decade since the passage of the Voting Rights Act.

Rucho vs. Common Cause, 2019

After a long court battle over North Carolina’s maps, the Supreme Court found that “partisan gerrymandering claims present political questions beyond the reach of the federal courts,” though it said nothing about the state courts. Racial gerrymandering, prohibited by the Voting Rights Act, remained illegal.

17.OK, so there is some protection.

Again, yes and no. Since Rucho, mapmakers could insist that a racial gerrymander was merely a partisan gerrymander if the racial group in question voted predominantly for one party.

Take Georgia, where Black voters make up nearly a third of the voting population and 88 percent of them supported Mr. Biden.

If Republicans in Georgia try to crack or pack predominantly Black districts, they could argue that their intent is merely partisan, not racist.

(Some lower courts have held that gerrymandering that dilutes the vote of a minority group is unconstitutional regardless of intent, but the argument remains in a legal gray area.)

18.Do you have an example?

Sure. Look at the district of Representative Terri Sewell, an Alabama Democrat. More than 60 percent of her constituents are Black, almost a third of the state’s Black population. The bulk of the state’s remaining Black population is split — or “cracked” — among the First, Second and Third Congressional Districts, all of which have been safely Republican for years.

Black voters in Alabama make up roughly 25 percent of the state’s population, and many civil rights leaders say the state should have two majority-Black congressional districts.

In 2018, a group of Black voters filed a federal lawsuit arguing that the Alabama map violated the Voting Rights Act. They lost.

19.Who likes this way of doing things?

Many incumbents do, for starters. Holding on to your job and political power is easier when you don’t have to worry about a tough challenge from the other party.

But in districts that are safest in November, lawmakers are finding great challenges in primary campaigns. In those contests, the most devoted partisans are often the most important constituency. And appealing to them is pushing incumbents and primary challengers alike to the political fringes.

All of which means that gerrymandering is fueling much of the polarization and extremism in American politics.

20.There’s that word again — gerrymandering. Where did it come from?

Gamesmanship in the creation of legislative districts is nearly as old as representative democracy itself. Britain had “rotten boroughs” for House of Commons constituencies until they were outlawed in 1832. In 1788, Gov. Patrick Henry of Virginia tried to deny his rival founding father James Madison a seat in Congress by drawing a district he wouldn’t be able to win. (Madison won anyway.)

The word gerrymander arose only in 1812, when Gov. Elbridge Gerry of Massachusetts presided over a new State Senate map that kept the opposition Federalist Party in the minority.

Elbridge Gerry’s Map, 1812

Mr. Gerry had the special misfortune of angering an editor at The Boston Gazette, who captioned a cartoon depicting a salamander-like state legislative district “The Gerry-mander. a new species of Monster.” The name stuck, and, two centuries later, is synonymous with crooked maps drawn for political advantage.

21.What’s different this year?

The timetable, for one. Delays in the census caused a scramble in drawing new districts, making it hard for incumbents and political newcomers to make timely decisions on whether to run.

This is also the first redistricting cycle without a protection under the Voting Rights Act known as “preclearance.” For decades, that required states with a history of voting discrimination to get federal approval before changing their voting laws or drawing new districts.

In 2013, the Supreme Court hollowed out the preclearance provision, leaving lawmakers in those states free to draw maps as they choose.

New maps could, of course, face legal challenges, but those challenges take time, and often fail.

22.Where is gerrymandering the worst?

Conditions are ripe when one party controls both of a state’s legislative chambers and the governor’s office. Republicans have complete control over the redistricting process in 20 states, Democrats in 10 states.

That gives Republicans unimpeded power to draw 187 House districts, and Democrats 75.

Democrats are most concerned about potential Republican gerrymanders in Ohio, Texas, Florida, Georgia and North Carolina. Republicans are on guard for Democratic gerrymanders in New York, Illinois, Oregon and Maryland.

23.Is there a fairer way to do this?

The short answer: independent panels everywhere.

But there is wide disagreement over how different factors should be weighted, like geographic continuity, competitiveness, minority representation and partisan fairness.

How Independent Redistricting Panels Work

All independent panels are not equal. Some are made up of equal numbers of Republicans, Democrats and independents. Others feature a nonpartisan chair as a tiebreaker. But all truly independent panels operate outside the legislature’s influence, at least mitigating bias in favor of incumbents.

24.Is anyone pushing for that?

Democrats in Congress initially sought to require independent redistricting panels in every state as part of the For the People Act, an omnibus voting bill that failed this year. Current proposals include banning partisan gerrymandering altogether and giving the courts greater power to intervene, but any such changes would most likely require Democrats to overcome a Republican filibuster.

25.What can I do?

Start thinking about 2030.

Control over redistricting hinges on control over state legislatures, which is determined in little-watched elections that are eclipsed by presidential races and statewide contests for Senate and governor. The redistricting process itself can often be changed only by a ballot initiative, which can take years — and a lot of people’s time and money — to organize and pass.

By the time the next redistricting cycle comes around, the die will be cast. Though nothing can stop you from going to a public hearing on your state’s new maps and giving the mapmakers a piece of your mind.

Related Coverage

How Texas Plans to Make Its House Districts Even Redder October 3, 2021
House Democratic Retirements Pile Up as Party Fears Losing Majority October 21, 2021
Illinois Democrats’ Map Aims to Grab 2 G.O.P. Seats in Congress October 29, 2021

An earlier version of this article misstated the number of House seats for which Democrats control the redistricting process. It is 75, not 84.