I'll cut-n-paste article because it is behind pay wall. Article is about congressional gerrymandering, but principles remain the same.http://www.nytimes.com/2014/01/26/opini ... tupid.html
Don’t Blame the Maps
JAN. 24, 2014
DO the Republicans owe their current congressional majority to gerrymandering? At first glance, it seems self-evident that they do. In the 2012 election, the Democrats won the popular votes for the presidency, the Senate and the House of Representatives. But somehow in the House — for whose seats Republicans controlled the redistricting process in many crucial states — the Republicans managed to end up with a 16-seat majority despite losing the popular vote.
The presumption among many reformers is that the Democrats would control Congress today if the 2012 election had been contested in districts drawn by nonpartisan commissioners rather than politicians.
But is this true? Another possibility is that Democrats receive more votes than seats because so many of their voters reside in dense cities that Democratic candidates win with overwhelming majorities, while Republican voters are more evenly distributed across exurbs and the rural periphery. Perhaps even a nonpartisan redistricting process would still have delivered the House to the Republicans.
To examine this hypothesis, we adapted a computer algorithm that we recently introduced in the Quarterly Journal of Political Science. It allows us to draw thousands of alternative, nonpartisan redistricting plans and assess the partisan advantage built into each plan. First we created a large number of districting plans (as many as 1,000) for each of 49 states. Then we predicted the probability that a Democrat or Republican would win each simulated district based on the results of the 2008 presidential election and tallied the expected Republican seats associated with each simulated plan.
The results were not encouraging for reform advocates. In the vast majority of states, our nonpartisan simulations produced Republican seat shares that were not much different from the actual numbers in the last election. This was true even in some states, like Indiana and Missouri, with heavy Republican influence over redistricting. Both of these states were hotly contested and leaned only slightly Republican over all, but of the 17 seats between them, only four were won by Democrats (in St. Louis, Kansas City, Gary and Indianapolis). While some of our simulations generated an additional Democratic seat around St. Louis or Indianapolis, most of them did not, and in any case, a vanishingly small number of simulations gave Democrats a congressional seat share commensurate with their overall support in these states.
The problem for Democrats is that they have overwhelming majorities not only in the dense, poor urban centers, but also in isolated, far-flung college towns, historical mining areas and 19th-century manufacturing towns that are surrounded by and ultimately overwhelmed by rural Republicans.
A motivated Democratic cartographer could produce districts that accurately reflected overall partisanship in states like these by carefully crafting the metropolitan districts and snaking districts along the historical canals and rail lines that once connected the nonmetropolitan Democratic enclaves. But such districts are unlikely to emerge by chance from a nonpartisan process. On the other hand, a Republican cartographer in these and other Midwestern states, along with some Southern states like Georgia and Tennessee, could do little to improve on the advantage bestowed by the existing human geography.
By no means does this imply that critics of gerrymandering are always wrong. In the states most frequently derided as overt Republican gerrymanders, our analysis shows that gerrymandering has indeed given the Republicans additional seats beyond the already pro-Republican average of our simulations. Most notable are North Carolina, Florida, Pennsylvania, Texas and Michigan.
But keep in mind that Democrats play this game as well. For example, by artfully dividing up Chicago into pie-sliced districts extending from Lake Michigan into the suburbs, the Illinois Democrats have done better for themselves than the outcome of our nonpartisan simulations. The Democrats have achieved something similar in Maryland. And in what will come as a surprise to many in the reform community, California’s redistricting commission produced multiple Democratic seats beyond the predictions of our simulations. Evidently the enormous and sophisticated lobbying efforts of California Democrats were successful.
All told, the Republican seat share emerging from the 2012 election exceeds our simulation predictions by only a small handful of seats: not nearly enough to deliver Congress to the Democrats.
In short, the Democrats’ geography problem is bigger than their gerrymandering problem. We do not mean to imply that the absurd practice of allowing incumbents to draw electoral districts should continue. Rather, we suggest that unless they are prepared to take more radical steps that would require a party’s seat share to approximate its vote share, reformers in many states may not get the results they are expecting.
Jowei Chen is an assistant professor of political science at the University of Michigan. Jonathan Rodden, a senior fellow at the Hoover Institution, is a professor of political science at Stanford University.