GC Jacobson redistricting maps

Gov. J.B. Pritzker signed the above redrawn maps for Illinois House, left, and Senate districts on June 4. (Each Senate district comprises two House districts.)

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On June 4, Gov. J.B. Pritzker signed new state House and Senate district maps into law. The Illinois Senate Redistricting Committee and Illinois Redistricting websites provided pictures of the proposed maps. They also allow anyone to draw their own and submit them for consideration.

Clearly, none of these external submissions were viewed as acceptable alternatives. So what are the people of Illinois getting with these new maps?

The Illinois Constitution only requires that maps be drawn to be compact (each district should be as tight as possible, much like a circle or square), contiguous (each district should be a continuous geographic body) and substantially equal in population (each district should have close to the same population). Any other properties or characteristics embedded into the maps are at the discretion of the redistricting committees.

When evaluating maps for any legislative body, there is the “eye” test and the “analytic” test.

The eye test is a visual inspection of maps and the shapes of the districts. Take, for example, the downstate district that includes both Springfield and Decatur. This may have been designed to give these two cities controlling interest in the outcome, effectively diluting the voice of the voters in the rural area between them.

On the other hand, to achieve population balance, several downstate urban areas need to be amalgamated into single districts. Similar efforts were made with the districts that include both Peoria and Bloomington, as well as Champaign and Danville.

However, the eye test cannot see the outcome of elections with such districts. That is when the analytic test comes into play.

There are metrics that capture characteristics of voters in each district. Redistricting committees avoid reporting such metrics prior to maps being voted into law, because they can expose gerrymandering on the part of those who drew them. These include efficiency gap, partisan asymmetry and competitiveness.

Efficiency gap measures the relative proportion of wasted votes for each party. Since a candidate can win their district by one vote or 10,000 votes, any votes above the requisite one-vote majority are wasted, and all votes for the losing candidate are wasted. A gerrymandered map will have a lopsided efficacy-gap measure, so one party loses significantly more than the other across the entire state.

Partisan asymmetry measures how shifts in voter support from one party to the other result in a change in the number of districts won.

If this measure is high, then one party has the potential to gain a large number of districts with a small increase in voter support, while the other will gain a small number of districts with a comparable increase in its support.

Competitiveness measures whether the maps will result in competitive elections, where candidates have to work to earn their votes and victories. If maps result in a low competitive measure, then candidates frequently run unopposed, or with an effortless path to victory.

How do the new Senate and House maps score? Since the Illinois Redistricting Committee did not post these numbers, our research group used the proposed maps and reverse-engineered the necessary census block data to make such evaluations.

On the two analytic metrics, efficiency gap and partisan asymmetry, the map proposed by the Illinois Redistricting Committee favors the Democratic party, though not to an extreme. On competitiveness, the proposed maps score poorly, with few districts likely resulting in competitive races.

Comparing the proposed maps to current maps, the metrics are similar, though overall less competitive. However, when evaluating the likely outcome in the next election, the new maps position Democrats to win two additional Senate districts and four additional House districts, everything else being equal. This is something that the committee did not want you, the voters, to know.

Although Republicans fight against gerrymandering in Illinois, in neighboring states like Wisconsin or Indiana, Republicans hold the redistricting power and draw maps to serve their interests. However, with a Democratic governor holding veto power in Wisconsin, that division of power will create more balance in their final maps.

These remapping efforts also serve as a precursor to when Illinois’ congressional district map is redrawn later in the year. There is nothing to prevent the same partisan process being followed and the same egregious results achieved.

Gerrymandering is not a Democrat or Republican problem, it is an ethical problem, and any political body or people that willfully gerrymanders or is complicit with such activities is exhibiting questionable ethics. Are these the people you want running the state?

Now that these maps are law, the stage is set for Illinois to have another 10 years of dysfunctional government, a structurally imbalanced tax system and other artifacts of gerrymandering, effectively excluding voters from the democratic process. It is no surprise that people are fleeing Illinois en masse.

You, the people of Illinois, deserve better. Remember that when you cast your vote in the next election.

Sheldon H. Jacobson, Ph.D., is a professor of computer science at the University of Illinois. His research group on computational redistricting is committed to bringing transparency to the redistricting process using optimization algorithms and artificial intelligence.

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