2016-01-14

Cities Split by Districting

I recently wrote about reform in Ohio that specifically calls out not splitting up municipalities when possible. How bad is it now? How do my maps fare? So, I wrote an analysis to check. Here's a preliminary result just for Ohio:
Standard Map: 226 places* split (24.1%)
My Map: 330 places split (35.2%)

Is that bad? I'm not sure. I would like to see a distribution of that over the size of the places split. Splitting a town of 4,000 people seems unnecessary, but splitting a city of 1,000,000 is inevitable. This is to be expected, given that the pure-compactness process explicitly does not care about any boundaries and any human process would at least look at that. If an official map broke up more cities, that would have to be the result of some horrific gerrymandering.

Given that I have this data, a future step would be to alter the solver to try not to split cities and towns. I might do a in-depth study of one state, such as Ohio, and see what the tradeoff between compactness and non-splitting is. At the limit would be following the hard rules in the new Ohio law that absolutely does not split unless there is no other way to make equal-population districts.



(*A "place" is Census bureau jargon that includes all kinds of cities, towns, villages, and some other kinds of municipalities. I'm counting the C1-C9 city-like incorporated areas, but not military bases or 'other'.)

1 comment:

  1. You are looking at the congressional map (I think?)

    The new redistricting standards only apply to legislative redistricting.

    In Ohio, the legislature does congressional redistricting, and did a very aggressive partisan gerrymander.

    The new amendment was proposed by the legislature, and was likely intended to head off alternatives being proposed by the initiative process.

    In the past, these initiatives have been sponsored by Democratic-leaning organizations, such as labor unions and the NAACP, and have had a political "fairness" component. One initiative failed because the proponents produced an example map with districts stringing out from northeastern Ohio to take advantage of the Democratic dominance in that area.

    The lightweight fairness version may have been to get enough votes to approve the constitutional amendment.

    Incidentally, I get a count of 69 split cities for the congressional plan, and if we ignore likely incidental splits (less than 1% of the municipality population), only 39.

    Akron city, Berea city, Bluffton village, Brunswick city, Carlisle city, Cincinnati city, Cleveland city, Clifton village, Columbus city, Cuyahoga Falls city, Delphos city, Dublin city, Fostoria city, Gahanna city, Grandview Heights city, Grove City city, Groveport village, Hilliard city, Huber Heights city, Loveland city, Magnolia village, Middletown city, Minerva village, Monroe city, New Albany village, New Holland village, Obetz village, Parma city, Plain City village, Reynoldsburg city, Ridgeway village, Rocky River city, Roseville village, Sharonville city, Springboro city, Tallmadge city, Toledo city, Verona village, Westerville city.

    Many, though not of all of these may involve cities that cross county boundaries.

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