The FiveThirtyEight Blog Releases the Atlas of Redistricting. The Maps are Impressive but Unusable


This week, the sports and politics polling blog FiveThirtyEight released its Atlas of Redistricting.  It takes a comprehensive look at the mapping possibilities for every congressional district in the nation, and is part of the site’s Gerrymandering Project, which seeks to uncover in their words, “[what] is greatly misunderstood . . .” about redistricting and whether “gerrymandering can (or should be) killed.”

The maps are impressive.  They produce congressional maps for seven common, but vastly different redistricting goals.  The result is that you get to see what your (or any) state’s congressional map would like if it were drawn as a Republican or Democratic gerrymander, a competitive map, a map that reflects the proportion of Republicans and Democrats in the state, a map that optimizes the number of minority districts, or maps that produce the most compact districts.

The trouble is; none of the maps would be legal.  The site does include a disclaimer that they are not purporting these maps to be legal either.  However, what they do not say, is that every single map drawn would be unusable in the real world.  A quick look at their methodology page says it all:

All of the hand-drawn maps follow two simple rules: Each district must be contiguous, meaning that all parts of the district touch each other, by water or by land.  And each district must be within 1,000 residents of the state’s “ideal” district population — the total population in 2010 divided by the number of districts — to satisfy the legal requirement that districts be equally populous.

If this is the case, this methodology makes each map a non-starter in every court in the country.  In redistricting, the “ideal population” is the number you are shooting for in terms of how many people are in each district.  In state legislative maps or local political maps, courts generally allow a “percentage” deviation of plus or minus 5%.  The map-drawer’s hard number of 1,000 residents, may or may not represent an overall deviation range of 10%.  But this standard is not the one that applies to congressional districts.

Congressional district maps must adhere to a much, much stricter standard than a deviation of 1,000.  In most cases, it’s more like one or two people.  As someone who has had to actually draw congressional maps – this is a much harder task.  The quote above on FiveThirtyEight’s methodology page links to the Equal Protection Clause of the 14th Amendment as the legal standard, which is not the legal standard used for determining whether a congressional district map is properly drawn in terms population equity.

It is common for redistricting observers to conflate the two standards for state legislative and congressional district maps, but the Supreme Court has been (uncharacteristically) clear.  The less strict legal standard in the 14th Amendment applies to state legislative maps, but the court views the apportionment clause of Article I, Sec. 2 of the Constitution as applying to congressional districts, and has held that it demands a much stricter application.  The court has said this in a line of cases without waiver; See Wesberry v. Sanders, (equality “nearly as is practicable”) Kirkpatrick v. Preisler ,(“precise mathematical equality”), White v. Weiser, (“mathematically equal as reasonably possible”).  There are exceptions to the rule, see Jefferson County Comm’n v. Tennant, but the standard is still precise equality.

At best, the Atlas of Redistricting is a rough thought experiment that can give us a good idea of what different redistricting priorities produce on a map – – just in very, very broad brushstrokes.

The accessibility of technology in the past decade or so has opened up the dark art of redistricting to many, but redistricting is equal part drawing and equal part law.  For a great summary on redistricting law, read the National Conference of State Legislature’s Redistricting Law 2010 or the “Red Book” as many call it.  Soon, the 2020 Red Book will be published.  As part of the editing team, I look forward to how the Supreme Court will rewrite it this decade.




Categories: Basics, featured, Gerrymanders, LATEST, Process and Politics, Redistricting, Technology

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1 reply


  1. Redistricting Weekly Update : Atlases and Mathematicians in the Fray

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