In 1812, Massachusetts Governor Elbridge Gerry and his compliant State Legislature redrew the lines of state senatorial districts in bizarre ad hoc ways to favor Gerry's Democratic-Republican Party. Thus was born the portmanteau word Gerrymander. [Portmanteau words, as Lewis Carroll explained, are words designed to carry several bits of linguistic clothing in a single piece of linguistic luggage. "frumious" is a portmanteau word, made from the fusion of "furious" and "fuming."] It has become commonplace in discussions of the present political contretemps to ascribe to gerrymandering the imperviousness of the Tea Party Republicans to widespread popular disapproval of their tactics, and there is no doubt a small element of truth in this bit of mainstream media wisdom. But it is worth pointing out that as a general explanation of what is going on, it is wrong.
The American political system is a winner-take-all system, as Professor Lani Guinier has pointed out in a well-known series of scholarly papers. Representatives are chosen from geographic districts [unlike the system in South Africa, for example], and a simple plurality of the votes cast gives the seat to a candidate. The result is that many of the votes cast are "wasted," in Guinier's evocative term. She means by this not the votes cast for other candidates [they may be frustrated, but they are not wasted], but rather all the votes cast for the winning candidate over and above those required to secure the election. If a candidate wins with 65% of the votes cast, as many U. S. Representatives of both parties regularly do, then almost a quarter of the votes that she receives are wasted, for she will win with or without them.
The centrally important fact about the distribution of voters inclined to vote for Democrats or for Republicans is that the voters are, to a truly remarkable extent, residentially segregated -- people tending to vote for Democrats [or Republicans] by and large move to places where there are many other people tending to vote for Democrats [or Republicans]. The reason for this is simple: voting tendencies are powerfully affected by income, by race, by religion, by ethnicity, and by level of educational attainment, among other things. Rich people tend to live with rich people, and rich people tend to vote for Republicans. Highly educated people tend to vote for Democrats, and highly educated people tend to live with highly educated people. There are Black neighborhoods, Latino neighborhoods, gay neighborhoods, Catholic neighborhoods, and so forth.
Unfortunately for the Democrats, their supporters are more highly residentially segregated than are the supporters of Republicans. Hence more votes for Democrats than for Republicans are wasted in elections. In the Senatorial and Presidential elections [but not in the election of members of the House] this anti-Democratic Party tendency is multiplied by the peculiar allocation of Senate seats and Electoral votes mandated by the U. S. Constitution.
It is in fact true that in the last two general elections, the Republicans have benefited somewhat from real gerrymandering -- from the drawing of geographically implausible district lines, following the 2010 census, to secure the election of Republicans. But that is not the principal source of their advantage in House elections.
What can supporters of the Democratic Party do? The answer is simple, but very unappealing: move to heavily Republican districts in sufficient numbers to overcome the Republican Party numerical advantage. Now, I am willing to give money to the Democrats. I am willing to walk door to door for the Democrats. But am I really willing to live my life in a hotbed of Evangelical Tea Party enthusiasts? There are limits to the sacrifices I will make for my ideals.