Stardate 20031008.2258

(Captain’s log): A reader sends this (but no first name, alas):

Sorry to present a topic out of school, but you are the only site I read that may attack the problem. My question is "How can gerrymandered legislative districts cause an entire state to fall in one camp or the other". It would seem that people can vote any way they like, and registration for party doesn’t guarantee a vote for the party candidate. I could agree that restricted areas such as parts (neighborhoods) of a city could be gerrymandered. However whole states, no. What do you think?

I guess it depends on what you mean by "the whole state". It would not directly affect any election which was held state-wide, such as for governor. But there are other ways it can matter, and it can matter a whole lot.

It has to do with the fact that our system is hierarchical and implements "winner take all". What that means is that at each level of hierarchy, the votes and influence of many voters are discarded completely when influencing the next level up.

Suppose that we have a state with five districts for state legislators. The districts are gerrymandered so that three of the districts have about 55% voters for party A and 45% for party B. The remaining two districts are 100% party B.

Party A would have three legislators but party B would only have 2, and A would be in control. But if you assume that all five districts have the same number of voters, then it turns out that party B actually has twice as many voters overall as party A.

If you arbitrarily assume 100 voters per district, it would mean that party A had 55+55+55+0+0 = 165 voters, while party B had 45+45+45+100+100 = 335 voters. But Party A would still have a legislative majority.

That, in general terms, is how gerrymandering works as it was practiced originally. You try to create a few districts which are extremely heavily dominated by your opposition, while creating a lot more where you expect your own party to have a small but sufficient majority. What that does is to dilute the value of the other side’s voters. Your 55 voters in one district have the same influence as 100 of theirs in another, while their 45 voters in your district have no direct influence at all.