The U.S. Supreme Court on Tuesday rejected Alabama’s attempts to prevent the redrawing of the state’s congressional map, meaning that the process of creating new district lines will continue.

Earlier this month, federal judges struck down Alabama’s new map, saying that it ignored the high court’s directive to design a second majority-Black district or “something quite close to it.”

The state’s Republican-dominated Legislature had initially made only one out of the seven congressional districts majority-Black, even though Black voters make up about 27% of the state’s population. The Supreme Court determined that this move likely violated the 1965 Voting Rights Act, which protects against racial vote dilution.

But Alabama defied the court’s order. It boosted the percentage of Black voters in the majority-white 2nd Congressional District from 30% to 39.9%, hardly giving that group a fair opportunity to affect election outcomes.

In other words, Alabama was attempting to racially gerrymander the state’s Black population into a single district — much as governments in the South did during Reconstruction to disenfranchise Black men, who’d just won access to the ballot box. (Black women’s constitutional right to vote wouldn’t come for at least another 50 years.)

But what, exactly, is a gerrymander? The term has seemingly gained more prominence in recent months, as several states face high-profile legal challenges to congressional maps said to be hostile to Black voters.

For instance, in July, the Supreme Court announced that it would hear oral arguments in a South Carolina racial gerrymandering case this fall. And in June, the high court laid the groundwork for the creation of another majority-Black district in Louisiana, after it tossed out the state’s appeal of a ruling that found that a previous map was a racial gerrymander.

Here’s what you need to know about the term, as the country navigates yet another season filled with disputes over maps that could shape Black voting power in upcoming congressional and state elections. But first, let’s take a look at something called redistricting.

What is redistricting?

In the U.S., redistricting is the constitutionally mandated process of redrawing the boundaries of congressional and legislative districts. State and local legislators do this every 10 years, following the census.

Our district maps are supposed to represent populations, not just land or trees, said Kareem Crayton, the senior director for voting and representation at the Brennan Center for Justice at New York University School of Law. So as an area’s population shifts, so must the congressional districts.

“Many democracies, including the U.S., have a rule that requires that our districts be roughly equally populated. This is the principle of ‘one person, one vote’: Your voting power should be the same, no matter where you happen to live,” he explained.

Redistricting, then, is a means of making sure that common demographic changes — when people are born or when people die or move — are reflected in the relative sizes of districts, and that Congress is, “in miniature, an exact portrait of the people at large,” as President John Adams put it in 1776.

This drive for fair representation is at the heart of an ongoing case in Georgia. A trial there ended just this month that could see the addition of another majority-Black congressional district in the Atlanta metropolitan area. Plaintiffs point to the fact that the state’s Black population grew by around half a million residents between 2010 and 2020.

What is gerrymandering?

If redistricting is about guaranteeing that everyone’s vote is equally weighted, then gerrymandering is about upending that principle. It occurs during the process of redrawing district boundaries, with the intention of designing maps with predictable election outcomes. State lawmakers in the dominant party may resist the influence of demographic change or undermine the power of a minority voting bloc.

Maybe you saw an illustration of the tactic in your high school government class: A popular 1812 political cartoon, sometimes attributed to Gilbert Stuart, shows a gerrymandered map as a winged monster, bearing its claws. The grotesque shape exemplifies the tortured boundaries that typically signal that those in power have gerrymandered a map.

The term “gerrymander” stems from this Gilbert Stuart cartoon of a Massachusetts electoral district twisted beyond all reason. Stuart thought the shape of the district resembled a salamander, but his friend who showed him the original map called it a “Gerry-mander,” after Massachusetts Gov. Elbridge Gerry, who approved rearranging district lines for political advantage. (Getty Images)

Gerrymandering comes in several different varieties: partisan, in which the controlling party secures or boosts its share of congressional or legislative seats; bipartisan, in which two equally represented parties bargain to protect their districts; and racial, in which legislators create district lines that prevent Black voters and other racial minorities from electing the candidates of their choice.

Both Democrats and Republicans manipulate maps. But Republicans have done so more aggressively in recent years. Further, their gerrymanders disproportionately burden historically disenfranchised groups, who lean Democratic.

That such maneuvering is undemocratic is beyond question, Tyler Daye, the policy and civic engagement manager at Common Cause North Carolina, a government watchdog group, told Capital B earlier this year.

“I don’t think that it takes a legal scholar to recognize that if you’re drawing your own districts, there’s a huge conflict of interest. I’d argue that you’d be hard-pressed to find a bigger conflict of interest in our government than state legislators drawing their own districts,” he said. “When the legislature draws these districts, it’s not concerned about keeping communities together. It’s not concerned about the citizens of the state. It’s concerned about drawing safe districts so that lawmakers can maintain their seats.”

Daye and many others advocate for independent redistricting commissions, which would have an equal number of Republican, Democratic, and unaffiliated members who aren’t lawmakers and be required to protect communities of interest, including racial and ethnic minorities.

What might this mean for Black voters?

The battles over maps could have profound political consequences in a number of states.

Since Black voters reliably back Democratic candidates, adding more majority-Black congressional districts would strengthen the party’s chances of reclaiming the U.S. House of Representatives, where the margins are tight.

Maybe more significant, Crayton argued, is the possibility of representation for areas where Black voting power has long been diluted, specifically areas in the South.

“There have been regions that have always been split,” he said, “despite there being identifiable Black communities there — communities with interests that are distinct from, if not totally in counterpoise to, those of the white Republicans who tend to represent these areas.”

Read more: ‘America Can Go Only as Far as the South Goes’

More accurate representation would have some effects on the local work that legislators can do for their constituents.

Consider that, in Alabama, only one of its seven House members — Rep. Terri Sewell, a Black Democrat — really champions Black voters, even though this group makes up nearly a third of the state’s population. Having a second person to represent Black voters’ interests, per the Supreme Court’s order, would go a long way toward easing that load, Crayton noted.

Khadidah Stone, who was a plaintiff in Allen v. Milligan, the Alabama case the high court decided in June, shared similar sentiments earlier this year. In particular, she underscored the difference that having fair maps can make when it comes to electing lawmakers who will move resources into Black communities.

“Some people might live in a neighborhood where they aren’t near a hospital or a school, or where they’ve had messed up roads for 10 years,” she told Capital B. “But then you go to another neighborhood not far away, and people there have the basic things they need.”

She asked: “What do communities do when they don’t have elected officials who will fight for them?”

Brandon Tensley is Capital B's national politics reporter.