Using algorithms to generate thousands of fair redistricting options
Traditionally, redistricting works like this: politicians draw one map behind closed doors, present it to the public, and say "take it or leave it." This process is:
Politicians meet behind closed doors
Draw one map
Present to public: "Take it or leave it"
Our algorithms create thousands of possible district configurations, each following legal requirements like equal population and contiguity.
We evaluate each plan using multiple criteria: compactness, demographic balance, and population equality.
The fairest 100 plans are presented to the community with full transparency about how they were created and scored.
We use a sophisticated mathematical technique called "Markov-Chain Monte Carlo" (MCMC). The algorithm starts with one map that is legally compliant and gradually improves it by making thousands or millions of small changes to reach a final map.
Each map is scored using established fairness measures: Compactness (how round the districts are), and Demographic balance (fair representation of all communities), Each map is evaluated using a combination of these metrics.
By generating thousands of maps, we create an "ensemble" that shows what fair districts naturally look like. This gives us a baseline to compare against and ensures our results aren't just one random outcome which may not be fair.
Every step of our process is documented and publicly available. You can see exactly how each map was created and scored.
Computers don't have political preferences. They follow the rules we give them and create maps based on fairness, not politics.
Instead of one option, communities get tens of different fair choices. They can pick the plan that best represents them.
All our maps follow legal requirements like the Voting Rights Act and equal population standards.
In Santa Clara County, our algorithm generated over 50,000 redistricting plans and identified 100 of the fairest options. Each plan was evaluated using:
Our algorithmic approach can work for any city, county, or region in California. Learn more about our methodology or get involved.