Michael West, a resident of Jefferson County, Kentucky, received a yellow card in the mail two weeks before Election Day notifying him that his polling place moved to an unfamiliar location. This change meant that he had to travel an additional mile to get to the polls. He believes that this change was enacted to discourage people from voting.
This story is not unique to just Michael West. Many states are consolidating precincts, changing polling place locations, or closing polling places entirely. Texas does this more often than any other state, closing over 403 polling places from 2013 to 2016 alone. And these changes have consequences. When polling places change, it increases the cost of voting. If the cost is too high, voters give up, leading to lower voter turnout.
Here in Texas, Waller County is under fire for the questionable selection of polling places and inconsistent operating hours. Located on the outskirts of the Houston metro area, Waller County has a population of 51,307 and is home to Prairie View A&M University, a historically black college.
During the first week of early voting in the 2018 general election, Waller County did not place any early voting locations in the city of Prairie View. During the second week of early voting, the Waller County placed only one early voting location in the city of Prairie View. That location moved around, too. For the first three days, the early voting location in Prairie View was at the Memorial Student Center. For the last two days of early voting, the early voting location was moved to the WC Community Center, an off-campus location.
This made it more difficult for residents of Precinct 309 (Prairie View A&M University) to vote early. There are 4,834 registered voters in Precinct 309. Of those that cast a ballot in 2018, 80% of voters in Precinct 309 voted early, which is higher than the 66% early voting average across Waller County.
But Precinct 309 had a significantly lower voter turnout (36%) compared to the county at large (51%). It’s possible that the distance and inconsistency of early vote locations turned away people who otherwise would have voted.
Five students from Prairie View A&M University, with the help of the NAACP, are suing Waller County for discriminatory practices in the selection of polling places.
Waller County is a Republican majority county, and Ted Cruz won with 61% of the votes. If there was a 100% voter turnout in Precinct 309, Ted Cruz would still win the election, but margin of victory would shrink from 23% to just 4%. This effectively puts Waller County in play for Democrats.
I wanted to use data to determine whether Waller County selected the best early voting locations for the 2018 election based on the thesis that everyone should have access to vote. I created an algorithm that creates early voting plans that best accommodate everyone in that area.
A good early voting plan is one that minimizes the average distance traveled to get to a polling place. I clustered people into a defined number of groups and mapped the distance of the cluster centroid to the nearest polling place. In doing so, I created an early voting plan that minimizes the distance everyone has to travel to go vote early. Then I compared my plan with Waller County’s plan.
Waller County’s early voting plan for the first week of early voting included these six locations:
- Waller County Courthouse
- Waller County ISD Administration Building
- Waller County Library
- Fieldstore Elementary
- Monaville Fire Department
- Katy VFW Hall
This plan resulted in voters traveling a median distance of 3.69 miles to get to the nearest polling location.
My proposed early voting plan for the 2018 would include these six locations:
- Adam’s Flat Building
- Waller County Annex
- Waller County Library*
- Turlington Elementary School
- Fieldstore Elementary School*
- Memorial Student Center on Prairie View A&M University’s campus.
* The asterisk indicates which polling places are the same in both plans.
My plan would result in voters travelling a median distance of 2.64 miles, a reduction of about one mile (or 27%) from Waller County’s plan.
In every early voting plan I generated, the optimal early voting locations included the Memorial Student Center at Prairie View A&M. However, Waller County did not include the Memorial Student Center as an early voting location in the 2018 election.
It’s not clear what the exact impact of these voting center locations had on the 2018 election. But three things are clear: there are a lot of student voters at Prairie View A&M, those voters tend to vote Democrat, and there are enough of them to make Waller County elections competitive.
I followed the steps below to generate my early voting plan:
- I geocoded every early voting and regular voting polling place in Waller County.
- I found the center of and the number of people in each census block group.
- With the centers of each census block group, I ran a K-Means clustering algorithm with a K of six in order to group the census block groups into six geographic regions and find center of those groups.
- At the end of each iteration, I map the center of each group to the nearest polling place. In the next iteration, I used the centers mapped to the nearest polling place as the new centers for the K-Means algorithm.
- The algorithm converges when the centers (polling places) do not change.
- I ran this twenty times and selected the result with the lowest sum of squared error.
I then compared the mean, median, standard deviation, and range of distances one would have to travel to vote early to see which plan was better and by how much.