How Mich. Rebuts Redistricting/Polarization Claims

How Mich. Rebuts Redistricting/Polarization Claims

By Sean Trende - October 15, 2013

Dave Weigel wrote a brief post on gerrymandering last Friday in response to my piece on the same topic. He used Michigan as an example of how Republicans were able to use redistricting to enhance their standing in the House, particularly by shoring up vulnerable members, thereby contributing to extremism.

Before responding, I think it’s important to note up front, as Weigel does, that this isn’t really a black-and-white issue, a fact that is easily glossed over. People run along a continuum of opinion regarding how much redistricting contributed to the GOP’s House majority and to polarization. We might place Tom Friedman at one pole, as he seemingly laid our increasingly divided nation at the feet of redistricting, Citizens United, and Fox News. At the other end are those political scientists who find little to no effect from redistricting. In the middle are people like Weigel, Charlie Cook, and myself, who think redistricting played a role, but who disagree -- sometimes strongly -- on the extent to which it mattered and how much other factors contributed.

From my point of view, redistricting helped Republicans gain between five and 10 seats that they wouldn’t have otherwise won, by shifting the median district rightward. But even this is more a function of polarization than a cause of it.

Weigel’s Michigan example is actually instructive in showing the limits of what redistricting contributes to polarization. At first blush, it looks like a classic case of a horrendously gerrymandered state. Barack Obama defeated John McCain by 16.4 percentage points there, more than twice his national average. Mitt Romney ran a much stronger race four years later, but the president still managed to win by a healthy 9.4 points. Yet under the Republican-drawn maps, the president ran better than his statewide 2008 showing in only five districts (of 14), and ran ahead of his national showing in just six. Romney carried nine of these districts outright.

As Weigel writes:

It’s not like gerrymandering created Justin Amash. It shored up Tim Walberg. Who's Tim Walberg? He was a Club for Growth-backed candidate who primaried a moderate Republican in 2006, lost in the 2008 Democratic wave, came back in 2010, and benefited when the new GOP legislature drew a map that packed Democrats in Detroit and Flint-centric districts, shoring him up to make no news but provide reliable "no" votes on anything that did not delay or defund Obamacare.

Weigel correctly notes that redistricting didn’t create Justin Amash, but instead shored up Tim Walberg. But its worth remembering that redistricting didn’t create Tim Walberg, either. As Weigel notes, Walberg (pictured) fits the mold of the type of polarizing legislator whose existence people blame on redistricting, but as Weigel also notes, he actually defeated a moderate Republican, Rep. Joe Schwartz, under the old lines. He went on to win handily in the general election, albeit against a weak opponent, before losing narrowly in 2008 to Mark Schauer. Walberg was back in 2010, and won by five points. In 2012, under the newly drawn lines, he won by 10 points.

Given this, it’s awfully hard to blame the redrawn lines for however conservative Tim Walberg is. It’s true that the old lines were also drawn by the GOP, but this particular district has leaned a few points more Republican than the country as a whole since the 1990s.

More importantly, how much was Walberg helped by redistricting? In one important way, redistricters helped him quite a bit: They removed Schauer’s home of Battle Creek from the district, thus preventing a rematch. This is the type of effect that is impossible to reduce to numbers, and may result in understating redistricting’s importance in elections.

But in terms of polarizing the lines and encouraging Walberg to adopt a harder line in Congress, it isn’t clear how redistricting would have had much effect. Obama won 52.7 percent of the two-party vote in 2008 under the old lines, and 51.7 percent of the vote under the new lines, a difference of 0.9 points (the difference is due to rounding). That would be categorized as a swing district that leaned Republican under both sets of lines.

More importantly, the redistricting wouldn’t have changed the outcome in any of Walberg’s races. Even under the new lines, he would have won in 2006, lost in 2008 and won in 2010. Under the old lines -- all other things being equal -- he would have still won handily in 2012. John Sides and Eric McGhee have run a similar simulation nationally and found that if you adjusted the candidates’ results for 2012 for the difference in partisanship between the old and new lines, only seven additional Republicans (net) would have lost; this effect vanished once Sides and McGhee took account of incumbency.

This is the nut of the problem. Pundits look at partisan control of redistricting, oddly shaped lines, and asymmetric outcomes, and have a tendency to assume that gerrymandering conferred some huge advantage. But when you dig down and examine the details, that’s often not the case.

Which brings us to Weigel’s third point, which is also his broadest. Did Republicans really “[draw] a map that packed Democrats in Detroit and Flint-centric districts, shoring [Walberg] up to make no news but provide reliable ‘no’ votes on anything that did not delay or defund Obamacare”?

Let’s get ourselves out of abstraction here, and look at the actual Michigan maps. The old lines are on the left, while the new ones are on the right:

As you can see, there’s a fair bit of continuity in the lines. This is unsurprising given the legislature’s likely desire not to rock the boat for too many incumbents, and the natural tendency to anchor each district to a population center.

When we look more closely at Detroit, we see districts that are more oddly shaped:

This looks like a terrible gerrymander. But there is actually something of a method to this madness. The GOP actually didn’t have much choice but to pack voters into Detroit- and Flint-based districts. Detroit has had two African-American-majority districts since the 1960s, and Republicans were probably required under the Voting Rights Act to retain both of them.

This was no easy task. The 13th and 14th districts had both seen their African-American populations drop below 60 percent, and both had suffered severe population losses in the 2000s, requiring them to take on quite a few additional citizens. Making matters worse, there were barely enough African-Americans in all of Wayne County to create two African-American-majority districts entirely within that county’s borders.

Since it was impossible (and possibly unconstitutional) to draw lines to make sure every African-American in the county was in the minority-majority district, redistricters needed to add those voters from Oakland County, which has a growing African-American population. This is actually the source of the odd appendage we see jutting northward from Detroit; it crosses Oakland County to take in heavily minority Pontiac. Even with all this, both districts are only 56 percent African-American and the 14th still elected a white Democrat over an African-American incumbent in the 2012 primaries.

The neighboring districts were then all pushed toward Republicans, as the most loyal Democratic constituents were removed to comply with the VRA. Even a Democratic legislature would have drawn something akin to these districts; there just aren’t many other options. No neighboring district is left with an African-American population in excess of 11 percent under this map, suggesting that the heavily African-American precincts in the state were pretty well gobbled up.

This is the core of the Democratic problem, not only in Michigan, but also nationally. These two districts each gave Barack Obama over 80 percent of the vote. This has serious implications for the remaining districts: The remainder of the state went for Obama by only eight points in 2008, roughly equal to his national average. The substantial Democratic voting advantage in the state is entirely spent on two districts.

Heavily Democratic Flint is big enough that there pretty much has to be a Genesee County-based district. I drew it to include some other industrial towns, like Saginaw and Bay City, but didn’t use the severe shape that Republican redistricters opted for. Add a district for the working-class whites in south central Wayne County (John Dingell’s district), send it south to Monroe County, and Obama only carried the remainder of the state by five points. Opt to send Dingell’s district westward toward Ann Arbor, a perfectly legitimate choice, and you end up with Obama carrying the rest of the state by four points. Because there’s no similar concentration of Republicans in the state, the remaining 10 districts will tend to lean Republican, as they do.

The point is that even a Democratic legislature, constrained by the Voting Rights Act, would have had a tough time drawing districts to mimic the state’s partisan tilt in the 2008 elections (roughly eight Democratic-leaning districts). The law requires too much packing, and the Democrats’ coalition is too naturally compact. A nonpartisan commission almost certainly would end up with something closer to the “perfect” GOP gerrymander than to the “perfect” Democratic gerrymander.

The same story repeats itself in states like Florida, Pennsylvania, and Ohio. It’s even true in Illinois, where Democrats stretched mightily to draw a map that resulted in Democratic representation in Congress roughly approximating Obama’s statewide share (with two of those Democratic seats looking wobbly over the long term).

That’s not to say that Michigan Republicans didn’t exercise their discretion to help the party out. It’s just to say that their ability was fairly minor, and heavily abetted by the state’s political geography. This chart shows each district in Congress, what Obama’s share of the two-party vote was under the old lines, and what it was under the new lines. For Gary Peters’ district, I used Hansen Clark’s old district as the baseline, since that was the VRA district under the old map. (Note also that the differences in the last column reflect rounding):

The only districts where Obama’s vote shares were radically altered were Peters’ and Sander Levin’s, where Democratic performance dropped off in large part as a result of shedding African-American voters. Kerry Bentivolio’s district, drawn to protect then-incumbent Thaddeus McCotter, went from having a slight Democratic lean to having a slight Republican lean.

None of these changes are enough to contribute significantly to polarization. To the extent that they do contribute, the gerrymander is probably a symptom of political geography, not the disease itself. 

Sean Trende is senior elections analyst for RealClearPolitics. He is a co-author of the 2014 Almanac of American Politics and author of The Lost Majority. He can be reached at Follow him on Twitter @SeanTrende.

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