Redistricting
Teaching
In 2017, I wouldn't have been able to tell you the definition of redistricting. When I first learned about redistricting in 2018, I was immediately hooked on the way that math, maps, and politics were so naturally intertwined. In my last semester as a graduate student at UConn in 2018, I put together some materials for a short unit in a general education math course I was teaching and I knew the story wouldn't end there.
In my first year at Trinity, I was fortunate enough to receive a faculty fellowship in Community Learning that gave me time and resources to develop an entire course on Redistricting. In Fall 2019, I taught Mathematics and Redistricting for the first time. As a cross-listed course between Math and Political Science, I covered many key mathematical ideas related to evaluating district maps, all components of the political process, many relevant court cases, and students even used the same software as many state governments to create their own maps. Students were also able to meet with Connecticut legislators that previously served on the state's Reapportionment Commission and even got a tour of the Legislative Office Building and the State Capitol where they happened to meet Governor Lamont! See Trinity's article.
With the inclusion of Census block-level data, I moved map-making to the amazing resource Dave's Redistricting for the second time I taught the course in the Spring 2021 semester. Even with many Covid restrictions, students loved applying their knowledge and skills to the new final project of creating a map portfolio demonstrating different objectives, including some creative gerrymanders.
The Fall 2021 semester might be my favorite teaching experience. I was able to have two sections of students take part in the redistricting process that was happening in real-time in Connecticut. Many students produced map proposals for Connecticut's congressional map, which became part of the Public Hearing Testimony for the Reapportionment Commission. One of my students won the Map Across America redistricting contest. We partnered with the League of Women Voters to preview State Senate and State House redistricting in key regions of the state. I participated in two panel discussions alongside key players in the state. My class was featured in a CT Mirror article. Finally, Trinity produced a feature article about the class. This group of students also produced some creative gerrymanders as a part of their final map portfolios.
I taught the course for a 4th time in Spring 2022 as we followed many new court cases and began the process of researching town-level district maps in Connecticut.
Topics covered in course
Math: population deviation, apportionment, compactness, efficiency gap, measures of partisan gerrymandering, measures of racial gerrymandering (ecological inference), MCMC methods (outlier analysis)
Politics/law: state processes, US Census, independent commissions, partisan gerrymandering court cases, racial gerrymandering court cases, prison gerrymandering, housing policy (redlining)
Research
In 2022, I received a grant from the League of Women Voters in Connecticut to analyze the new General Assembly (House and Senate) state maps in terms of the protection of the incumbent politicians. First, we mapped the (publicly available) addresses of all incumbents and overlaid their addresses with the old (2012-2021) and the new (2022) districts. We then looked at the precinct-level results from the 2020 election and looked at the precincts that changed districts to determine if the changes would project to benefit the incumbent, hurt the incumbent, or have a neutral effect. Finally, we conducted a MCMC (Markov Chain Monte Carlo) analysis with an ensemble of 20,000 valid district plans to compare the enacted plan with respect to incumbency protection. See the paper here.
State House (151 districts)
Looking at the 30 most competitive State House races from 2020 and the precincts that changed districts, we projected 16 to benefit the incumbent, 13 to have a neutral impact, and only 1 to hurt the incumbent. Sure enough, all 16 projected benefits retained the same party affiliation after the 2022 elections. Furthermore, of the 6 most closest races from 2020 projected to favor the incumbent, all 6 were won by the same candidate by wider margins. Statewide, the number of races within 5% fell from 23 to 15.
Other than the one "new" district that moved across the state to Wilton due to population shifts, the remaining 150 districts were all drawn to contain a single incumbent. In other words, no incumbents were paired and forced to run against each other. Unsurprisingly, this was confirmed as an extreme outlier by our MCMC analysis where only 52% of districts (on average) contained a single incumbent. It is worth noting that Connecticut prioritizes keeping town borders intact as much as possible and they were somewhat sacrificed with an average of 108 town splits in the ensemble compared to 72 in the actual plan.
State Senate (36 districts)
Of the 9 most competitive elections in 2020 and the changed precincts in the new map, 7 were projected to benefit the incumbent's party and the other 2 were projected to have a neutral impact. Sure enough, all 7 projected benefits retained the same party in the 2022 elections and only 1 district of the 36 flipped party affiliation.
Similar to the House, the MCMC analysis confirmed the enacted map as an extreme outlier as all 36 districts were drawn to contain a single incumbent compared to the 52% of districts (on average) in the ensemble. It turns out that town borders were not sacrificed in the Senate as the actual plan has 38 town splits compared to 36 (on average) in the simulated plans.
In some Connecticut towns, redistricting also takes place on the town level. In many towns, voting districts simply exist to divide the town into voting locations but in some towns, voting districts actually correspond to representation for municipal elections. In other words, at least some members of a Town Council (or Representative Town Meeting) correspond to districts within the town as opposed to all members being elected at-large. See this page for all towns and maps.