Gerrymandering: Drawing the Line Dora Richardson, Dr. Matthew Petering Industrial and Manufacturing Engineering, University of Wisconsin - Milwaukee Ingrahm, C. (2014, May 15). America’s most gerrymandered congressional districts. (2019). Retrieved from https://www.washingtonpost.com/news/wonk/wp/2014/05/15/americas-most-gerrymandered-congressional-districts/

Gerrymandering Definition Practice of manipulating district boundaries to create political districts to give a particular party electoral advantage Maximizing the number of districts controlled by one party Concentrating the voting power of the other party into fewer districts Gerrymandering is the practice of manipulating political district boundaries to exaggerate the power of a particular party so the number of districts it controls is maximized and the voting power of the other party is concentrated into fewer districts.

Political Districts Three types of districts: Progression of Wisconsin Congressional Map Since 1973 Three types of districts: U.S. Congress State Senate State House Fundamental aspect of U.S. democracy Redrawn every 10 years based on latest census data Redistricting equalizes district populations to compensate for population movement Political districts are the fundamental unit of representation within U.S. democracy at both the national and state levels. According to U.S. law, every ten years three types of political districts must be redrawn based on the latest census data. The purpose of redistricting is to equalize district populations to compensate for population movement. Wisconsin's congressional districts. (2019). En.wikipedia.org. Retrieved 11 April 2019, from https://en.wikipedia.org/wiki/Wisconsin%27s_congressional_districts

Who Draws the Map? Redistricting Case Summaries | 2010-Present. (2018). Retrieved from http://www.ncsl.org/research/redistricting/redistricting-case-summaries-2010-present.aspx

Gerrymandering In the News North Carolina's congressional districts. (2019). Retrieved from https://en.wikipedia.org/wiki/North_Carolina%27s_congressional_districts Maryland's 3rd congressional district. (2019). Retrieved 10 April 2019, from https://en.wikipedia.org/wiki/Maryland%27s_3rd_congressional_district Williams, P. (2019). Supreme Court to hear gerrymandering cases against Democrats, Republicans. Retrieved from https://www.nbcnews.com/politics/supreme-court/supreme-court-hear- gerrymandering-cases-against-democrats-republicans-n986716

Gerrymandering In the Courts Federal courts have jurisdiction to consider constitutional challenges to state legislative redistricting plans. Baker v. Carr (1962) Apportioned substantially according to population. Exception from strict population equality to give representation to minorities and create compact districts of contiguous territory. Districts should be redrawn at least every 10 years. Reynolds v. Sims (1964) A district becomes an unconstitutional racial gerrymander if race was the “predominant” factor in the drawing of its lines. Miller v. Johnson (1995) Four partisan gerrymandering cases came to the Supreme Court. Gill v. Whitford – Wisconsin’s 2011 congressional map Benisek v. Lamone - Maryland 2011 congressional map Rucho v. Common Cause - North Carolina’s 2016 congressional map Turzai v. League of Women Voters of PA – Pennsylvania’s 2011 congressional map (2018) Gerrymandering In the Courts Baker v. Carr (1962) Federal courts have jurisdiction to consider constitutional challenges to state legislative redistricting plans. Reynolds v. Sims (1964) Apportioned substantially according to population. Districts may deviate from strict population equality to give representation to political subdivisions and provide for compact districts of contiguous territory. Districts should be redrawn districts to reflect population shifts at least every 10 years. Miller v. Johnson (1995) A district becomes an unconstitutional racial gerrymander if race was the “predominant” factor in the drawing of its lines. (2018) four partisan gerrymandering cases came before the Supreme Court. Redistricting and the Supreme Court: The Most Significant Cases. (2018). Retrieved from http://www.ncsl.org/research/redistricting/redistricting-and-the-supreme-court-the-most-significant-cases.aspx 

Examples of Districting Criteria for Political Districts Not Compact Fair 2R – 3B Compact Unfair 5B Statewide Party Preference: 40% Red, 60% Blue Requirements: Population equality Contiguity Desired: Political fairness Compactness Competitiveness Example 2: perfect representation, but not compact Primary goal: Political fairness i.e. Proportions match  (proportion of seats won in state) ~=~ (proportion of party votes received in state) Other Objectives: Contiguity voting wards must be connected Population equality Compactness minimize perimeter of voting district, while maximizing area enclosed Competitive

States With Seat Difference ≥ 2 1st Stage of Research States With Seat Difference ≥ 2 Identify U.S. states in which the political districts may have been gerrymandered Results of the November 2018 U.S. Congress elections Difference between the proportion of U.S. congressional seats won and the proportion of votes received by each party

States with ≥ 20% seat difference: U.S. House seats allocated to each state after 2018 election U.S. House Election Results 2018. (2019, January 28). Retrieved from https://www.nytimes.com/interactive/2018/11/06/us/elections/results-house-elections.html

2nd Stage of Research Early phase of algorithm formation Create a user-friendly computer program to automatically generate voting districts for any U.S. state Displays a digital map of proposed voting districts that are legally acceptable and minimize gerrymandering Run multiple times to produce varying maps Can create political districts for U.S. House of Representatives, state senate, and state house elections 2012-2020 WI Election Data with 2017 Wards. (2019). Retrieved from https://data-ltsb.opendata.arcgis.com/datasets/62d5782482cd45f2898fe7e3d4272c10_0

Details of Algorithm A heuristic algorithm Assigns indivisible, existing electoral wards to districts Four goals: contiguity, population equality, compactness, & political fairness