Skip to main content
Government & Politics

A Nationwide Primer on Redistricting

Graphic from Stateline.

By Tim Henderson

Redistricting debates will heat up in many states as Democrats try to stop Republicans, who control most statehouses, from drawing district lines that would solidify their political power for another decade.

Every 10 years, after a new census count, states adjust the boundaries of state legislative and U.S. House of Representatives districts to account for population shifts. The 2020 census was shortened by the pandemic and the results have been delayed, putting some states in a bind: The numbers needed to draw new districts might not arrive until late summer or fall, when candidates typically launch their campaigns.

In states such as Florida, Georgia, North Carolina and Texas that have conservative legislatures and liberal cities, Republicans will try to preserve their majorities by drawing congressional and state legislative districts that favor GOP incumbents and dilute Democratic voting strength.

Midwestern swing states where redistricting battles raged 10 years ago are bracing for a renewed struggle—especially Pennsylvania and Wisconsin, where Republicans control legislatures but Democrats occupy the governor’s office.

“After the red wave in 2011, you had some really aggressive line-drawing in places like Ohio, Wisconsin and Pennsylvania,” said Michael Li, a redistricting expert at New York University’s Brennan Center for Justice, during a seminar sponsored by the National Conference of State Legislatures. “Now I think the hot spots are going to be in the South—North Carolina, Florida, Georgia, Texas.”

Paul Brace, a political science professor at Rice University in Houston, predicted that in the current redistricting process, Southern Republicans may go on the defensive to protect their existing political advantage as cities diversify and attract more Democrats from other states.

“Virginia may have been the tip of the spear,” Brace said. “It transitioned from pretty conservative, to toss-up, to pretty solidly Democratic, driven by migration to cities from other states moving them into the Dem column. That was definitely the case with Georgia, and Texas is on this trajectory as well.”

Texas and Florida also had the largest population growth of the decade, making their latest mapmaking efforts more complex.

In North Carolina and Texas, federal courts over the past decade intervened to redraw Republican-created districts. But the U.S. Supreme Court has diminished the role of the federal courts by eliminating the Voting Rights Act requirement that some Southern states “preclear” their maps with federal officials, and by deciding that state courts should rule on partisan gerrymandering cases.

The Supreme Court dropped the preclearance requirement for states—most of them in the South—with a history of voter discrimination in its 2013 Shelby County v. Holder decision. It also ruled that all purely partisan gerrymandering cases be decided in state courts in Rucho v. Common Cause in 2019.

Another reason state courts will take on a larger role this decade is the increased number of states with new rules for drawing districts, which could attract legal challenges. Ohio, for instance, added a rule that the proportion of Republican- and Democratic-controlled districts should reflect statewide voter preferences. California, Iowa, Montana and Nebraska banned the use of party registration data in drawing districts.

In Maryland, Gov. Lawrence J. Hogan Jr. (R) is appointing a commission composed of three Republicans, three Democrats and three independents to recommend congressional and legislative district lines that he’ll introduce in the General Assembly. But Democrats have supermajorities in the Senate and House, and they’re almost certain to advance their own maps — and aren’t obligated to ratify the governor’s proposals.

Turning to commissions

A decade ago, Republicans were savoring their victories from a nationwide offensive called REDMAP (for Redistricting Majority Project), flipping 660 legislature seats and gaining “trifecta” control (both legislative chambers and the governor’s office) of 20 state governments, compared to only 11 for Democrats. Previously, Democrats had trifecta control in 16 states, compared to only nine for Republicans.

In North Carolina, for example, both chambers of the legislature flipped Republican in 2010, giving the GOP the power to redraw maps. But in 2011, courts struck down the boundaries as unfair to racial minorities. Pennsylvania, where the state House flipped in 2010 to give Republicans control of the legislature, saw its congressional districts redrawn by a state court because they violated state laws by breaking up too many cities and towns.

Texas saw particularly extensive litigation, with maps drawn, redrawn and redrawn again by federal courts between 2011 and 2018 to correct districts judged to be unfair to racial minorities. And in Florida, where Republicans secured a trifecta in 2011, state courts revised districts based on new criteria imposed by a citizen initiative.

During the last redistricting process, courts intervened to change the maps in a total of 19 states, mostly to make them fairer to Democrats and minority voters. In Maryland, Hogan in 2019 accused the Democratic-led legislature of gerrymandering and called for an independent commission. The U.S. Supreme Court threw out a challenge to the Maryland maps.

The constant lawsuits and partisan acrimony have prompted some states to take redistricting out of the hands of state lawmakers and give it to independent commissions.

In the past decade five states (ColoradoMichiganNew YorkOhio and Utah) adopted some form of commission, compared to one or two in previous decades. In 2018, Missouri voters approved the appointment of a nonpartisan demographer to draw the lines, but in November voters opted to return to a method that will hand the responsibility to panels made up of Democratic and Republican loyalists.

A total of 19 states now have commissions with input on redistricting, and another five use commissions as a backup if the legislature can’t agree or overcome a veto, said Wendy Underhill, director of elections and redistricting for the National Conference of State Legislatures.

“I’ve started to advocate more for a commission, if only because this system makes the branches of government mad at each other,” said Peter Wattson, who worked for the Minnesota Senate from 1971 to 2010 and has become a nationally recognized redistricting expert. Minnesota still relies on legislators to draw the lines. “We could all be friends and blame the commission.”

Wattson, a Democrat, now speaks to state officials on how to draw maps that will stand up in court. He agreed with many experts that Republicans engaged in “outrageous gerrymandering” after the last census. (The term “gerrymandering” derives from Elbridge Gerry, who as Massachusetts governor from 1810 to 1812 created a partisan district in the Boston area that was likened to the shape of a salamander.)

But Republicans defended the redistricting after the last census as a movement to make state legislatures reflect growing conservative sentiment.

“Project REDMAP went to donors and said, ‘Hey, state legislatures draw congressional and legislature maps that last for a decade, so help us go win these legislature races. Period,’” said Adam Kincaid, director of the National Republican Redistricting Trust, a group that advises Republicans on redistricting strategy.

“We won those races on maps drawn by Democrats, so I think people agreed with our policy agenda,” Kincaid said. He added that he opposes commissions, most of which were added by citizen ballot initiatives, because they “amend state constitutions through the back door,” taking that power away from legislatures.

‘Packing and cracking’

Legislators typically use a strategy known as “packing and cracking” to dilute the voting strength of the minority party. “Packing” places the opposition in a few highly concentrated districts. “Cracking” spreads the opposition’s remaining voters across majority-dominated districts, diluting their voting strength so they are unlikely to ever win.

“I call them polarized districts,” said Kimball Brace, a Virginia-based redistricting consultant. “Where Republicans are still in power, you’re going to continue to see these polarized districts that pack minorities into the smallest number of districts possible.”

Such strategies, aided by computer technology, allow “the majority to draw districts that pack and crack the partisan minority in such a way as to minimize the possibility of their ever becoming a majority,” making it possible to win elections with a minority of the statewide vote, Wattson said.

Another change is the growing public awareness of the power of redistricting. Many states have added more public hearings and input on the process, even allowing citizens to propose new maps in Michigan, Missouri and Ohio. New technology such as a redistricting lab at the Massachusetts Institute of Technology also allows voters to make their own alternatives for consideration.

“The public is going to be much more aware of the process and involved,” said Jeff Wice, an attorney for the New York state Assembly, speaking at the NCSL event. “The best redistricting is not a power grab when the politicians pick their voters, but when the voters pick their politicians through a fairer redistricting process.”

Stateline is a nonprofit news service that provides reporting and analysis of trends in state policy. It is an initiative of The Pew Charitable Trusts. See Josh Kurtz of Maryland Matters contributed to this report.


Our stories may be republished online or in print under Creative Commons license CC BY-NC-ND 4.0. We ask that you edit only for style or to shorten, provide proper attribution and link to our website. Please see our republishing guidelines for use of photos and graphics.

If you have any questions, please email [email protected].

To republish, copy the following text and paste it into your HTML editor.


Creative Commons License AttributionCreative Commons Attribution
A Nationwide Primer on Redistricting