The highly anticipated Supreme Court ruling on Louisiana v. Callais will affect the Voting Rights Act, which led to the creation of majority-minority districts in many states. Without such districts, gerrymandering of congressional maps could be taken to an unprecedented level, effectively making House elections meaningless — perhaps even unnecessary.
Congressional map-drawing no longer needs to be done manually. Computational redistricting provides algorithms to create maps with scalpel-like precision. Computers can provide highly gerrymandered districts for either party, based on who runs the mapping process. What is less discussed is that computational redistricting can also create maps that serve the interests of voters. They can also create competitive districts that force candidates to be responsive to their constituents rather than their party.
In other words, computational redistricting is a tool that can be used either for good or for evil.
The weapons of gerrymandering are known as “packing” and “cracking.” “Packing” assigns as many voters as possible with the same political lean into the same district. Although such voters overwhelmingly win their district, only a 50 percent win is needed, effectively wasting votes that could have influenced the outcome in other districts. For examples of this, look to Illinois’s 15th and 16th districts, which were both won by Republicans uncontested in 2024.
“Cracking” achieves a similar outcome, albeit in a complementary manner. By distributing voters with a common political lean across multiple districts, it dilutes these voters’ influence so much that they cannot gain a critical mass of support for their favored candidates. A good example of this is Tennessee’s 5th congressional district, which includes parts of Democrat-leaning Nashville. Ever since the 2021 gerrymander, the district has been represented by a Republican. The new Missouri map similarly cracked metropolitan Kansas City so that there is no longer a Democratic district there.
The requirement for majority-minority districts has generally favored Democrats. In 2024, there were 148 such districts. Of these, 122 were won by Democrats and 26 by Republicans. If majority-minority districts are ruled to violate the 14th and 15th Amendments of the Constitution, then computater redistricting can be weaponized to create maps that not only favor the party that controls the map-drawing process but also scoops up nearly every district in the state.
Algorithmically, requiring majority-minority districts imposes a constraint that limits how gerrymandered maps can be. Other constraints include compactness, equal population districts and contiguity, which all serve similar roles. Requiring communities of interest to be preserved would be a reasonable surrogate for majority-minority districts, by limiting cracking of like-minded groups.
Several state use redistricting commissions to create maps, including the largest Democrat-leaning states — California and New York. In a new redistricting environment, without the requirement of majority-minority districts, not securing all or most of their 78 seats for Democratic candidates would make getting a Democrat House majority exceedingly difficult. On the other hand, Republican-leaning states like Texas and Florida, with their 66 seats, would easily be able to draw most seats for Republican candidates.
This can get complicated very quickly. For example, for California to abandon its redistricting commission for the 2026 midterms will require voter approval. They are trying to get it next month through a ballot measure. They chose this path to counter the redrawn Texas map that creates five additional Republican-leaning districts. Several other states are actively pursuing new maps in this gerrymander arms-race. All such efforts show disrespect toward constituents, the very people Congress is charged to serve.
Let’s never forget how this began. The president asked for more Republican seats in 2026 so that his party could hold the majority for two more years.
Several states have more balance across the two parties, based on the 2024 election results, making capturing nearly all the seats by one party more challenging. These include such traditional battleground states as Arizona, Georgia, Michigan, Minnesota, Nevada, North Carolina and Pennsylvania. However, a partisan redistricting commission dominated by legislators from one party can always unleash the power of computational redistricting algorithms to grab a sizeable majority of districts that favor their party candidates.
The end result is that most House seats will have a predetermined outcome, effectively making voters superfluous in the election process. Based on where people live, and the packing and cracking of them into gerrymandered districts, politicians will take full control of the election process and outcome.
It does not need to be this way. Even with the most gerrymandered maps, voters still need to show up and cast their votes. In battleground states, there will remain a handful of competitive districts. Voters can also choose to vote in a manner that undermines the gerrymander process.
How the Supreme court rules in Louisiana v. Callais is more than just the constitutionality of the Voting Rights Act, and whether one party gains a permanent stranglehold on our political process. It elevates computational redistricting into a position of influence on shaping our democratic process. An algorithmic tool that can create maps with scalpel-like precision can either make elections a vehicle for voter presentation or voter suppression. That is what is at stake when the Supreme Court issues its final verdict in the case.
Sheldon H. Jacobson, Ph.D., is a computer science professor in the Grainger College of Engineering at the University of Illinois Urbana-Champaign. As a data scientist, he uses his expertise in risk-based analytics to address problems in public policy.
