Mapping tools released: Anyone can draw new Bloomington city council districts

Screenshot of the mapping tool created by the MGGG Lab at Tufts University loaded with Bloomington data. The image links to the mapping tool: Pick “Cities” then “Bloomington”

Late last week, the MGGG Lab at Tufts University released a mapping tool that makes it easy for anyone to draw new boundaries for Bloomington’s city council districts.

The release is part of a web-based redistricting resource the lab has developed, called Districtr. The Bloomington module of Districtr was created at The B Square’s request.

The acronym MGGG stands for Metric Geometry and Gerrymandering Group.

The re-drawing of city council districts is normally a once-a-decade chore that has to be completed in the second year following the decennial census. The census count came in 2020. That means this is the year for city council redistricting.

The idea is to balance out the population of the six council districts, if their populations have shifted too much over the last 10 years. Bloomington’s council districts have, in fact, become imbalanced, based on the 2020 census.

The release of Bloomington’s Districtr module comes about two weeks after Bloomington’s city council enacted amendments to an ordinance that in late 2020 created a redistricting advisory commission. The ordinance revisions relaxed the membership eligibility requirements—in an effort to get an adequate pool of eligible applicants.

The commission was supposed to be seated at the start of 2021. But no members have been appointed, yet, because of an inadequate candidate pool.

Responding to an emailed B Square question, city council administrator attorney Stephen Lucas wrote that this coming Friday (June 10) would likely be the earliest date that appointments would be made. That’s because he advised the three at-large council members—who form the appointment committee—to wait at least 15 days after a May 26 news release was issued about the new eligibility requirements.

Under the local ordinance, the council is supposed to get an initial recommendation from the redistricting commission in early September.

An amendment to state law, made by the state legislature earlier this year, gives the council until the end of the year to make the final redistricting decision, not just until Nov. 8.

Still, for potential candidates mulling a run for city council in 2023, it is already getting late. Just seven months remain until the window opens in early January 2023 for declarations of candidacy to be filed.

The availability of tools that anyone can use to draw district maps makes it feasible that several alternative maps could be ready for consideration by the commission—just as soon as members are appointed and their meetings start.

The B Square has created a map repository to facilitate the aggregation of such maps in a place where anyone can comment directly on a map in the collection.

In addition, The B Square has taken a software program called Auto-Redistrict for a spin, based on Bloomington’s precinct shapes and population totals from the 2020 census.

The software uses an iterative process to cycle through and evaluate very large numbers of maps, winnowing out the worst of the bunch, letting the better maps “mutate,” and eventually settling on a map that has evolved as optimal—based on the parameters set at the start. The two basic parameters are compactness and population balance, which can be weighted using sliders.

That means maps generated by a computer algorithm could easily be a part of the mix of new districts considered by Bloomington’s redistricting advisory commission.

Auto-Redistrict was created by Wisconsin-based programmer Kevin Baas. Those who install the free open-source software and run it might have a couple of the same questions as The B Square.

Among the questions: When does the program stop iterating?

It doesn’t, Baas wrote, in response to a B Square question. When the interactions settle into basically the same map returned over and over for a while, the calculations can be manually stopped. After the interactions have been stopped, the status of the map can be saved in a data file. On The B Square’s machine it took about a half hour for Auto-Redistrict to settle on any map based on Bloomington data.

Baas’s software uses a “random” process for selecting mutations. Here’s what the software looks like as it is cycling through iterations of possible maps.

Screen Recording Snippet of Auto-Redistrict

The selection process for the members of the city’s redistricting advisory commission also features a random element. From each of the five sets of two potential appointees, which will be determined by the council’s appointment committee, one of them is supposed to be selected by a coin flip.

Based on communication to The B Square from council administrator/attorney Stephen Lucas, the earliest that any coins will be flipped is Friday (June 10).


[Answers from Auto-Redistrict software developer ]

[Bloomington precinct shape files with population totals]