Just because something is bad, doesn’t mean that all other bad things are associated with it. Or to put it another way, Hitler did not invent cancer. And yet when there is a bad thing, especially a bad thing we don’t fully understand, we have a tendency to associate all sorts of other bad things with it.
Take gerrymandering, for instance. Gerrymandering is the process by which state legislatures draw state and congressional district lines, in order to maximize partisan gain. It is commonly assumed that gerrymandering increases the power of incumbents. (Here and here, for two examples.) And one recent New York Times article even asserted that gerrymandering is partly responsible for increased partisanship. Both of those claims are false.
Of course, gerrymandering is bad. It creates confusion among voters about who represents them, thereby undermining the ability for voters to communicate with their representatives. Gerrymandering can reduce the political power of certain constituencies and minority groups, by carving their communities up into tiny blocks spread across multiple districts. Gerrymandering can even cause representatives to lose their connection to their district; an urban member of Congress from an urban district one year may find herself the next running for reelection in a largely suburban and rural district.
But gerrymandering does not increase the power of incumbents, at least not as a general rule. Incumbents want stable, safe districts. The necessities of gerrymandering require that district lines change with every census. After all, the people responsible for gerrymandering are not interested in any individual’s best interest. They are interested in maximizing the number of seats won by the party, which requires constant alteration based on changing demographics. Every time that the lines are redrawn, there is the possibility that once unsafe districts will become unsafe.
Gerrymandering is also not responsible for the increase in partisanship. Think about it. In a Blue State, where the Democrats draw the district lines, how do they do it? Remember, in politics margin of victory doesn’t matter. So they create a lot of districts that are 60%-40% Democrat, and then a couple districts that are as close to 100% Republican as they can muster. So, in a gerrymandered Blue State, the Democrats are all drawn from districts that lean Democratic–but these are not hyper-liberal districts. And the Republicans are from hyper-conservative districts… but hyper-conservative by Blue State standards, which by national GOP standards is probably fairly moderate. (In that sense, I wouldn’t exactly expect the average Alabama Democrat to be a socialist.) That doesn’t sound to me like a formula for increasing the partisanship in Congress. Besides, gerrymandering is a constant in American politics, and has been for almost 200 years. They’ve steadily gotten better at it over time with new technology, but the ebbs and flows of partisanship doesn’t exactly match up well with the steady increase in technological progress.
So, yes, gerrymandering is bad. District lines should be drawn by non-partisan (or at least bipartisan) committees, not by partisan legislatures. They should be as stable as possible, and should try to keep neighborhoods and communities together, when possible–not carve them up for partisan advantage. But if you want to explain incumbency or partisanship, look someplace else. Gerrymandering has nothing to do with that; blaming gerrymandering is simply a distraction for other problems.