What's the Difference Between Redistricting and Gerrymandering?

By: Dave Roos  | 
gerrymandering graphic
When does redistricting tip over into gerrymandering? Noun Project

Representative democracy is a beautiful thing, but the process of drawing the lines for congressional and state legislative districts can get ugly.

The Constitution is vague on how voting districts should be drawn, saying only that they should be updated every 10 years and be roughly equal in population. Over the centuries, American politicians have seized on the once-a-decade redistricting process to redraw voting maps to their advantage. While partisan redistricting is an accepted if bemoaned practice, the courts have found it unacceptable to redraw voting districts for the express purpose of suppressing the voting power of Black voters and other racial minority groups.


Gerrymandering is the manipulation of voting districts for hyper-partisan or racist reasons, but the line between legit redistricting and unethical gerrymandering is blurry at best. It's ultimately up to judges to decide whether a redistricting plan is kosher or not.

Quick Primer on Voting Districts

Every 10 years, the United States conducts a census. The constitutional purpose of the census is "apportionment," the process of determining how many seats each state should have in the House of Representatives. While the Constitution automatically allots two senators for every state, the apportionment of representatives in the 435-seat House is based on population, with populous states like California getting 52 representatives (as of the 2020 census) and sparsely populated states like Wyoming and South Dakota only getting one seat each.

Members of the House are voted into office by the voters in their congressional district back home, and according to the Constitution, those districts should each be approximately the same size, meaning that each of the 435 House members represent roughly the same number of people. The average congressional district now holds 761,169 people. The same is true for state legislatures. Both state senators and state house members represent specific voting districts that are divided equally among the state's population.


Who draws the district maps? A handful of states appoint independent commissions to draw their district lines, but those are the outliers. Right now, state legislatures in 39 states draw their own congressional districts, including the six states that only have one congressional district. And it's a similar story for state-level voting districts, where 34 state legislatures have full control of the process.

Redistricting Senator Will Brownsberger
Co-chairs of the Special Joint Committee on Redistricting Sen. Will Brownsberger and Rep. Mike Moran (out of frame) speak about the recently released draft maps of the state legislative districts at Ashburton Park in Boston, Oct. 12, 2021.
Erin Clark/The Boston Globe via Getty Images

If the state legislature is firmly in the hands of one political party — as it is in more than half of all states — then that party exercises a lot of control over the redistricting process. By tweaking the size and shape of voting districts, they can boost the voting power of their party and increase the odds of winning congressional and state legislative seats.

But when does partisan redistricting cross the line and become illegal gerrymandering?


The Rules of Redistricting

When state legislators sit down to redraw their voting district maps, even in solidly Republican or Democratic states, they are expected to play by some basic rules, says Doug Spencer, a law professor and election law scholar at the University of Colorado Boulder:

  • Districts have to be of roughly equal population; a deviation of a few percentage points is OK
  • Districts have to be contiguous, meaning they have to be contained by one boundary
  • Districts should be compact, not long and snake-like

Of those three characteristics, the compactness (or non-compactness) of a district is usually the one that triggers accusations of gerrymandering, says Spencer, who also manages the website All About Redistricting. "If you see a bizarrely shaped district, that raises your antennae that it may not have been drawn neutrally, but in a way that favors some group: a political group, a racial group or something else."


gerrymander cartoon
The original gerrymandered district: This 1812 political cartoon was a reaction to the newly drawn state senate election district created by the Massachusetts legislature to favor the Democratic-Republican Party. The bizarre shape of the district was likened to a salamander and labeled “the Gerry-mander” after its creator Gov. Elbridge Gerry.

After all, it was the freakish shape of a Massachusetts congressional district that helped coin the term "gerrymander" in 1812. The long and snaking district was approved by Gov. Elbridge Gerry and delivered a powerful electoral advantage to his party, the Democratic-Republicans. A newspaper cartoonist noted the salamander-like shape of the district and labeled it "the Gerry-mander" after its partisan creator.


Partisanship Alone Isn't Illegal

According to Spencer, the courts have recognized that partisanship in the redistricting process is an accepted outcome of state elections. If voters put control of the state legislature in the hands of one party, then there is an expectation that party officials will make redistricting decisions that benefit their party.

"The question becomes, how much partisanship is too much?" says Spencer. "That's a line that's hard to distinguish."


Some state legislatures are blatantly honest about what they are trying to accomplish with redistricting efforts. In North Carolina, the Republican chair of the state's redistricting committee said in 2016, "I propose we draw the maps to give an advantage to 10 Republicans and 3 Democrats, because I do not believe it is possible to draw a map with 11 Republicans and 2 Democrats." And in Maryland, the Democratic governor testified that a new district was drawn to "create a district where the people would be more likely to elect a Democrat than a Republican, yes, this was clearly my intent."

Do such statements go too far? For its part, the Supreme Court is keeping out of the controversy. In 2019, the justices ruled 5-4 that the nation's highest court would not get involved in challenges to state redistricting plans on strictly political grounds. They left those challenges to state lawmakers and state courts.


Racial Gerrymandering Is Still Outlawed

Racially motivated gerrymandering is unconstitutional under the 14th Amendment guarantee of equal protection under the law. But before the 1964 Voting Rights Act was passed, state legislatures in the Jim Crow-era South used a pair of gerrymandering tactics to strip Black voters of equal electoral power: packing and cracking.

"It was a strategic choice," says Spencer. If Black voters were concentrated in certain geographic areas of a state, then the legislators would "pack" them into one or two districts. Even if that created strong Black voting blocks in those districts, their vote would be outweighed by all of the majority-white districts.


If Black voters were more geographically dispersed, then the districts were drawn in order to "crack" or dilute the Black vote by assigning small numbers of Black voters to several different districts. In that way, their voices were guaranteed to be drowned out by the white majority.

That was supposed to change with the Voting Rights Act, which included a provision that six Southern states had to receive federal approval for their redistricting plans. Those six states — Alabama, Georgia, Louisiana, Mississippi, South Carolina and Virginia — were flagged for extra scrutiny because of a history of race-based gerrymandering. In the 1970s, three more states were added: Alaska, Arizona and Texas.

But in a landmark 2013 case, the Supreme Court "bailed out" those nine states from having to seek congressional preapproval for their redistricting plans, stoking fears of a new wave of racially motivated gerrymandering in Republican-controlled Southern legislatures.

"In [the 2021-22] cycle, for the first time since the 1960s, state legislatures can redistrict without getting their plans reviewed and approved by the federal government," says Spencer.

Fair maps rally
A Fair Maps Rally was held in front of the U.S. Supreme Court on March 26, 2019, in Washington, D.C. The rally coincided with the Supreme Court hearings in landmark redistricting cases out of North Carolina and Maryland.
Sarah L. Voisin/The Washington Post via Getty Images


When Courts Step In

The reality is that racial gerrymandering is still unlawful and can be challenged in both state and federal courts. A lawsuit intended to block a state's redistricting plan on racial grounds must be filed by a voter of color living in the district, says Spencer, not an outside political organization. It's then up to a judge or judges to determine if there's enough evidence to conclude that the district lines were, in fact, drawn to disenfranchise minority voters.

"The judge's job is to evaluate the evidence — testimonies, emails and texts between lawmakers, etc. — to suss out if the redistricting decisions were merely partisan, which is allowed, or was in reality about race," says Spencer.


There were two high-profile Supreme Court cases in recent years in which redistricting plans were rejected on grounds of racial gerrymandering:

  • In Cooper v. Harris, the Supreme Court upheld a lower court's decision that the 2011 redistricting plan passed by the North Carolina legislature was a racial gerrymander because it packed Black voters into two congressional districts. The court rejected the state's argument that redistricting was done on purely partisan grounds.
  • In Bethune-Hill v. Virginia Board of Elections, the Supreme Court effectively blocked Virginia's 2011 redistricting plan on the grounds that racial quotas were a leading factor in how the lines were drawn. The Virginia legislature created 12 districts, each with at least a 55 percent Black voting age population.

What makes the line between redistricting and gerrymandering so blurry is that the electorate has become increasingly polarized along racial lines, says Spencer. In the 2020 presidential election, 92 percent of Black voters chose the Democratic candidate, Joe Biden. Meanwhile, white voters continued to skew Republican in 2020, particularly non-college-educated whites, 65 percent of whom voted for Donald Trump. What that means for Republican-held legislatures, especially in the South, is that any attempt to crack or pack Democratic districts risks targeting Black voters.