Let's talk redistricting for a second.

Updated: Jul 15, 2020

Thanks to Missouri's Wonky Week/It Starts Today Missouri


In 2018, 62% of Missouri voters approved Clean Missouri - an ethics reform package that changed how districts are to be drawn (among other things).

It called for a number of changes, including using a nonpartisan state demographer. But it also called for using partisan fairness in the redistricting formula, as determined by the "efficiency gap."

The what-sa-what?

The efficiency gap. It measures partisan bias of a district by looking at how many votes are "wasted" by each party.

It's a lot easier to explain the efficiency gap by looking at an example. (Hat tip to Ryan Best, Visual Journalist at FiveThirtyEight.com. He has lots of cool stuff at his website, which you should check out: www.ryanabest.com)

Here's a picture of a perfectly proportional district. Forty seats, divided equally between red and blue. In the example below, two seats are won by each party - which would be expected based upon the partisan makeup of the district.

But below is a picture of the same districts - with the same number of votes on each side - that are drawn in a way that "wastes" some of the votes. You can see that one district is 100% red - that's called "packing," because it's packing as many members of one party into a district as possible.

The other three seats are an example of "cracking" - splitting voters up in such a way that they are almost guaranteed to be a minority in that district.

The "wasted votes" come into play in this second example, because any vote over 50% is a vote that a party didn't need to get to win, and any vote for a losing candidate didn't matter to the outcome. So wasted votes are any votes over 50%, and all votes for a losing candidate.

In the example above, only six votes are needed to win each district. That means any votes above 6 are "wasted," as are any for a losing candidate.

Blue wasted two votes. Red wasted 14.

The result? In the first proportional example, both parties won 50% of the vote and got 2 seats each. In the second gerrymandered example, even though both parties won 50% of the vote, blue got 3 seats and red got one.

That's why the efficiency gap matters.

And that's why the Missouri GOP is losing their collective mind that Clean Missouri requires an efficiency gap analysis.

It's also why they have introduced a measure that will roll Clean Missouri back. Of course, they don't frame it that way. According to the Republican bill sponsor, their proposal takes legislative redistricting “back to a similar process that we have used before — I would argue successfully — for decades."

But how do they do that?

By increasing the acceptable "efficiency gap" to 15%.

But what the heck does that mean? How good or bad is 15%?

Well, for reference, the example of cracking and packing that we looked at above - where red winning 50% of the vote led to them gaining just ONE seat while blue netted THREE - has a partisan efficiency gap of 15%, benefitting blue. Under the Republican proposal, that would be perfectly acceptable.

Hopefully that helps demonstrate that their "ethics proposal" guts the efficiency gap requirement.

What can we do about it? Well, you can call your state representative and your state senator and let them know what you think of this idea. Then tell your friends and neighbors to do the same. (*And while you're at it, tell them to join It Starts Today Missouri to make sure Democrats can run in every district!)

Read the national coverage of this insanity here: https://www.nytimes.com/aponline/2020/01/14/us/politics/ap-us-redistricting-missouri.html

And a bonus: you can play around with gerrymandering Congressional districts with FiveThirtyEight's interactive tool. You can see what Congressional districts would look like if districts were drawn to favor Dems, Republicans, or some other factor (including competitiveness). https://projects.fivethirtyeight.com/redistricting-maps/#Dem

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