This might sound harsh, but it is pure partisan cheerleading to think that Democrats, with a one-percentage point edge in the national vote for the U.S House of Representatives, would have blessed Nancy Pelosi with the speaker's gavel last year. The harsh reality is that, in order to seize a House majority, the Democrats are probably going to need a bigger cushion than even the 1.4 million vote edge they took last year.

And that is because the "it's not all about gerrymandering crowd" does have some political science to back them up.

The New Republic's Nate Cohn addressed the issue back in February when he wrote:



But even if redistricting were non-partisan, Republicans would possess a modest advantage in the chamber. Democrats do even better in cities than Republicans do in rural areas, so even a fair process would pack a larger number of Democratic voters into strongly Democratic districts.

This type of "geographic clustering" is based on a very simple premise:segregation.

African-Americans have spent decades as the most loyal voting bloc in the Democratic coalition, and the past several elections have also seen a steady movement of Latino voters into the "loyally Democratic" column. If either voting bloc congregates together in one community, that community is inevitably going to be terribly one-sided come election time.

And those are two ethnic groups, as it happens, that tend to be clustered tightly in ethnic enclaves in the larger cities of the United States, as well as other pockets of rural America (the Rio Grande River valley in Texas and Alabama's "black belt" of rural counties near the Mississippi border are excellent examples).

Ergo, even if you drew perfectly compact maps, you'd probably see a situation where there would be a large number of districts where Democrats would absolutely throttle the GOP, because of the high concentrations of African-American or Latino voters nestled within those districts. That would "throw off the curve" on those national numbers, because almost all of that 1.4 million vote edge is going to be owed to ... if you crunch the numbers ... less than 10 districts that are so deep blue that the margins are simply ridiculous.

Consider: if one looks at the Daily Kos Elections compilation of how all the 435 House districts voted for president last year, you'd see that the most one-sided Republican district in the nation was TX-13, an absurdly right-wing slice of rural Texas represented for nearly two decades by Rep. Mac Thornberry. Mitt Romney snared 80.2 percent of the vote in the 13th district.

You would also see that there are ... wait for it ... 25 Democratic House districts that are more one-sided in favor of the blue team. The most Democratic district in the nation? Jose Serrano's district in the Bronx is the winner, with 96.3 percent of the district vote going to Barack Obama in 2012.

Lest you think that this alone is proof of rampant gerrymandering, remember that a large number of those districts came from states where Republicans did not control the pen in the redistricting process (nearly a half dozen, for example, came out of California).

What's more, under the previous maps, where the Democrats had a healthy majority at one point, this phenomenon was still present. By going back to 2008, the recent high-water mark for Democratic majorities in the House, we see that there were a total of 87 districts in the country where Obama beat McCain by a two-to-one margin or greater. There were only 21 districts nationwide where McCain beat Obama by a similar margin. Of course, some of that is owed to the fact that Obama beat McCain nationally by a healthy margin, but that doesn't explain the gap in total.

So, does that mean that the defenders of the Republican majority are correct, and that gerrymandering played little-to-no role in the perpetuation of a GOP House majority?

Nah.

Residential patterns explain some of the disparity between seats and votes, but it would be absolutely asinine to say that it explains it completely. If that were true, I'd make this challenge to the GOP House majority and all of its defenders in the public conversation: do a mid-decade redistricting, in every state, entirely by independent commission (a la Iowa or California). After all, if the GOP House majority can be explained entirely by geographic clustering, there'd be nothing to lose, right?

George Mason University professor Michael P. McDonald jumped on this subject earlier in the month. The entire article is worth a read, but here is a key point:



Upon some reflection by anyone who has drawn a redistricting plan -- and I've been a redistricting consultant in 14 states -- geography is not really constraining on congressional redistricting. Congressional districts are very large. In moderate- to large-sized states they consist of over 700,000 persons. It is easy in all but the most densely-urban areas to combine urban, suburban, and rural voters within a compact district. And again, the plans implemented in the states with the largest urban centers are not responsible for the current partisan imbalance among the congressional plans.

McDonald very subtly makes two incredibly important points here. For one thing, the sheer size of American congressional districts make it easy to draw "fair districts," if that is the goal. For another, the districts where geographic clustering are the most obvious are in states where the lines were drawn in such a way that Democrats actually do quite well. Of the 25 most one-sided districts in the nation, 15 of them came in three states: California, Illinois and New York. Democrats drew the lines in Illinois. California was drawn by a newly created independent commission in a map that was more favorable to Democrats than the previous one. And New York was the result of a court-drawn map that largely held in place the overwhelming Democratic majority in the delegation.

When people talk about Republican gerrymandering, they aren't talking about those three states. They are talking about Ohio. About Michigan. About Pennsylvania. About Florida. And about North Carolina.

North Carolina, in particular, is a real case study in the impact of gerrymandering. When Republicans snared control of the legislature in 2010, their redistricting efforts (which, in a curious quirk of state law, could not be vetoed by the state's Democratic governor) were ambitious to say the least. In the previous incarnation of the state's maps, the median district in the U.S. House was 47 percent Obama in 2008: a point or two behind his statewide result there, but generally in line with the statewide outcome. As would be expected in a closely contested state, Obama won a majority of the vote in six of the state's 13 CDs. After the NC GOP finished their handiwork, the median district in the state's U.S. House delegation was 41.7 percent Obama. The president scored a majority in just three of the state's 13 districts in 2012, despite only performing only slightly worse in the state between 2008-2012. But in those three districts, he scored a higher percentage of the vote (between 71-78 percent) than he did in any of the Tar Heel State's districts in 2008, when he carried the state.

What's more: Obama's 4th best performing district in the state? An 11.9 percent win for Mitt Romney in the reconfigured 13th district. The Democrats were not only packed into a trio of districts, but the remaining 10 districts were essentially rendered uncompetitive, with the sole exception of conservative Democrat Mike McIntyre somehow clinging to his seat in a district that went 59-40 Romney.

Now, it seems incredibly implausible that the voters of North Carolina somehow dramatically reclustered themselves in four years. So, in this case, the argument that residential patterns drove the result would take a pretty ignorant GOP cheerleader in order to make it. Just as it would be equally ignorant to claim that the current imbalance of the House delegation there (9-4 Republican) accurately reflects the will of the people in the state. This was the purest example of a gerrymander one can find.

The other states mentioned were not quite as naked, but they were notable nonetheless. And "geographic clustering" partisans would probably be quick to point out that those states are not necessarily gerrymandered, because of Democratic vote sinks in each state (Philadelphia in Pennsylvania, Columbus and Cleveland in Ohio, etc).

But Working America's Seth Michaels took that point head on earlier in the month, with an awesome example to the contrary:





@sethdmichaels geographical sorting matters a lot, but if gerrymandering didn't matter, Southeastern PA wouldn't be drawn like this. http://t.co/...

Well, yeah ... that looks pretty compact, doesn't it?