How to Identify Partisan Gerrymanders

As redistricting season heats up across the country, one word that is constantly repeated by the media and politicians alike is “gerrymander.”

This odd sounding word, defined as “the dividing of a state, county, etc., into election districts so as to give one political party a majority in many districts while concentrating the voting strength of the other party into as few districts as possible,” has equally odd origins. Although it sounds like it might be related to “meander” – as in the twisting, curving shapes of the manipulated district lines – it is actually derived from the shape of a Massachusetts state senate district drawn two hundred years ago by then-Governor Elbridge Gerry that was said to resemble the shape of a salamander. Hence the Gerry-Mander.

When the public hears the word “gerrymander” in the news or at a political press conference it is almost always used to describe oddly shaped district lines. But just because a district has an odd shape does not automatically mean that it is a gerrymander. District lines sometimes must twist and bend to follow concentrations of minority populations in order to accommodate the demands of the Voting Rights Act, which requires that areas with majority-minority populations receive the opportunity for fair representation. Districts might also have odd shapes in order to follow county or town boundaries.

In fact, there’s one way to identify gerrymanders that doesn’t involve looking at the maps at all. The best way to identify if your state has a history of partisan gerrymandering is to examine the election results, namely the relationship between the number of seats a party wins, and its percentage of the popular vote in those elections.

If a party is winning a significantly greater percentage of seats than its percentage in the corresponding statewide popular vote, then a partisan gerrymander is afoot. After all, districts are supposed to be drawn in accordance with the principle of one person- one vote.

Let’s use New York as an example. New York State has a long, well-known history of partisan gerrymandering in the state legislature. Since 1974 the Democrats have held an iron grip on the State Assembly and the Republicans have controlled the State Senate (with the exception of 2008-2010).  With redistricting in New York conducted by a task force controlled by the legislature itself, gerrymandering has been a key tool for each party to ensure its continued dominance in its respective half of the legislature.

When we compare the percentage of the statewide popular vote won by the Democrats in the Assembly and the Republicans in the Senate with the number of seats won, the results are striking. Since 1974, without exception, the Democrats in the Assembly and Republicans in the Senate have often won 5-10% more seats than their share of the popular vote would suggest.

As many as 20 seats in the Assembly and 6 seats in the Senate swing to the column of the party in charge of drawing the maps. In New York, each party is highly adept at using gerrymandering to maximize the number of winnable districts by packing voters from the other party into as few districts as possible.

The same test can be applied to evaluate your state’s districts for partisan gerrymandering.  If there is a stark inequality between a party’s statewide popular vote total and the number of seats it won in the election, then chances are the party who had that advantage is probably the party that controlled the redistricting process. This method of proving partisan gerrymandering can be an effective argument for an improved redistricting process this time around.