1. 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

2. 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.

3. 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

4. Who Draws the Map?
Redistricting Case Summaries | 2010-Present. (2018). Retrieved from

5. Gerrymandering In the News
North Carolina's congressional districts. (2019). Retrieved from
Maryland's 3rd congressional district. (2019). Retrieved 10 April 2019, from
Williams, P. (2019). Supreme Court to hear gerrymandering cases against Democrats, Republicans. Retrieved from gerrymandering-cases-against-democrats-republicans-n986716

6. 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

7. 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

8. 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

9. States with ≥ 20% seat difference:
U.S. House seats allocated to each state after 2018 election
U.S. House Election Results (2019, January 28). Retrieved from

10. 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
WI Election Data with 2017 Wards. (2019). Retrieved from

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