Data & Code (PGP)


A collaborative project to collect precinct geographies and election data from across all 50 states, D.C., and the five U.S. territories, to empower citizens in advance of the 2021 redistricting.

Gerrymandering Test Code (MATLAB)

Run the three gerrymandering tests presented on this site, and replicate the analyses reported in Three Tests for Practical Evaluation of Partisan Gerrymandering.

Virginia precincts and demonstrative map

Contains relevant precinct-level results and a demonstrative map for undoing the racially gerrymandered districts in the southeastern corner of Virginia. More detail at our GitHub repository.

Gerrymandering Test Code (Python)

Run the three gerrymandering tests presented on this site, as well as several other common gerrymandering metrics.

Geoprocessing Code

A loose collection of utilities for various geoprocessing operations that are common in the study of redistricting. Work in progress.

State Legislative Election Results, 1971–2018

Contains the results of over 80,000 single-member state legislative election from 1971 to 2016.

Congressional Election Results, 1948–2018

Cleaned results of each Congressional election from 1948 to 2016.

Useful Links


A community of interest mapping tool created by a team of Princeton undergraduates with help from PGP.

Runaway Redistricting: How the Rush to Redistricting Can Leave Communities Behind

With the adjusted census timeline, states will receive population data needed for redistricting several months later than in previous census cycles. Common Cause details, in this report, the likely impact of this new schedule; in addition to recommendations for ensuring a transparent and inclusive redistricting process.

Extreme Maps

A 2017 report by the Brennan Center on the district maps produced in the 2011 redistricting cycle.

Dave's Redistricting App

A free-to-use, public software for drawing and analyzing state legislative and congressional district plans.

All About Redistricting

A great resource maintained by Justin Levitt. Go here to find out, for instance, which parties controlled redistricting for various states in various years.


A free-to-use, public software created by the Metric Geometry and Gerrymandering Group for drawing state legislative and congressional district plans as well as communities.

The State of Redistricting Litigation

A tracker updated by the Brennan Center.

How Changes to the 2020 Census Timeline Will Impact Redistricting

A comprehensive analysis by the Brennan Center of how possible census delays will affect redistricting in 2020.


Visualize the efficiency gap across time, and upload custom district plans for analysis.

Scholarly Work

Data & Code (Non-PGP)

State Legislative Election Results

Carl Klarner's collection of state legislature elections from 1967–2016.

Daily Kos Elections Data

Daily Kos Elections maintains an archive of useful data on recent elections, including presidential election results by Congressional and State Legislative district, district maps, demographic information, and much more.


Code by Ben Fifield et al. to generate hundreds of thousands of alternative district plans.

Elections Geodata

An open-source effort to collect precinct-level geographic shapefiles.

Markov chain district sampler

C++ code by Wes Pegden et al. to sample among many similar district maps in order to determine if a map is highly unusual.


An open-source effort to collect precinct-level election results.


Python code by the Metric Geometry and Gerrymandering Group at Tufts to generate alternative districting plans.