DistrictBuilder: A Free Software Tool for Redistricting

With the 2020 Census in motion, journalists, politicians, community leaders, and members of the public are looking ahead to redistricting: the process of drawing new legislative district boundaries based on population changes. Partisan gerrymandering has pulled redistricting out of an academic niche to a mainstream news topic, but in many states, the redistricting process is far from transparent, and legal battles for fair districts are ongoing.

Today, we’re excited to relaunch DistrictBuilder, a free and open source redistricting software tool that empowers the public to draw legal redistricting maps across the country. You can start drawing right now:

Block-level redistricting data

By law, new state district plans must balance the population equally between districts using the new data from the 2020 Census. As mappers begin drawing new electoral maps, they need the most detailed data from the Census available. Census blocks are the smallest unit of census population geography and are necessary to draw any legal redistricting plan.

Previously, this kind of detailed mapping was only available to state agencies with budgets large enough to pay for proprietary software that could handle it. When we began revamping DistrictBuilder in 2017, we made it a top priority to support block-level data in every state, and we’re excited to make this data available to everyone for free, something unprecedented in a publicly available tool.

Draw legal redistricting maps using block-level data

With block-level data, mappers can more accurately measure the efficiency gap, compactness, contiguity, and other measurements of partisan gerrymandering, making access to the most up to date block-level data critical in the fight for fair legislative districts.

As soon as the 2020 Census data comes out, we’ll make it freely available to the public to start mapping. Until then, you can try out our block-level mapping in DistrictBuilder today, using data from the 2010 Census.

An intuitive user experience

DistrictBuilder is built (ha!) with the user in mind. It has an intuitive modern interface that makes it easy to use. A few features that we’re really excited about:

Real-time updates

Don’t worry about waiting until you’ve finished drawing a district to know how your district demographics are changing. Use the rectangle tool to draw and your district stats will update in real-time.

Use the rectangle tool to select multiple geounits at once and update your results live.

Cancel or accept changes

Easily add selected areas to the right district. Finalize your choice by selecting “Accept”. If what you drew doesn’t work, try again by hitting “Cancel”.

Population labels

And we have population labels! A mapper can easily see the relevant populations without needing to hover over every single geounit.

Add in population labels from the dropdown menu to quickly see the population in every geounit.

And we have more improvements coming! Over the next several months, look for features like undo/redo, keyboard shortcuts, and more. Check out our public roadmap to follow along.

Supporting public redistricting

DistrictBuilder makes it easy for anyone to draw a fair map and join in the fight against gerrymandering. In the last redistricting cycle, DistrictBuilder was successfully used by advocacy groups and nonprofits to raise awareness about redistricting and to drive change for fair legislative districts.

Draw the Lines PA uses DistrictBuilder to engage members of the public in the redistricting process by hosting competitions to draw the fairest redistricting maps.

Robust sharing features, evaluation tools, and the ability to hold redistricting competitions for members of the public all play a key role in making DistrictBuilder the best platform for open redistricting. We’re excited to support old and new partners alike with our refreshed modern, free, and open source redistricting software that will empower them to build a better map for everyone.

Draw your own custom redistricting map

DistrictBuilder is free and available to anyone starting today! Whether you are a journalist, community leader, elected official, or member of the public, we invite you to start drawing now.