You may have seen in the news that the Republicans are almost guaranteed to hold the House of Representatives majority, regardless of the outcome up-ballot. But, how can everyone be so sure? The reason is because of an age-old tactic of gerrymandering.

Gerrymandering is the setting of electoral districts, and the process of redrawing district lines. Historically, the intent of gerrymandering is to realign based on moving populations and changing population density in a state. However, redistricting has more often than not been used in political gerrymandering, or redrawing electoral districts to help one political party or an incumbent representative. The way this works is by drawing districts so that a high concentration of a representative’s supporters reside in a single district, almost guaranteeing reelection.

For example, assume that there is a state that is 60% democrat. A fair distribution of the electoral districts would lead to say three democrat representatives and two republican representatives. Redrawing the districts however, can lead to any combination of representatives – by putting the majority of democrats in two districts, the party split can be three republicans and two democrats.

In the 2012 election, we saw gerrymandering efforts from the 2010 census seriously affect the outcome of the congressional elections. Democrats received over a million more votes than Republicans, but Republicans took the house 234 vs 201 representatives. In New York, Democrats received 66% of the popular vote. However, Republicans received 21 of the 27 available seats. In Pennsylvania, Democrats won 51% of the popular vote, but only 1/3 of the House seats.  

Another conflict with gerrymandering is that it can be used to limit the power of the minority vote. Racial gerrymandering will concentrate minorities into fewer districts, thus limiting their power elsewhere and overall. These districts are called majority-minority districts, as in a specific minority will hold the majority in a district. In June, the Supreme Court agreed to hear a case (a second time) on this subject in Bethune-Hill vs Virginia Board of Elections.

So how does this play out in the 2016 Congressional elections? Many Republicans are faced with a double-edge sword: either they denounce Trump and lose a large part of Trump’s base’s votes or support Trump and face backlash from many more moderate Republicans. However, maybe they need not worry. Thanks to gerrymandering, it is estimated that as few as 10% of the House seats are competitive. Even if Democrats hold their current seats, and win all the competitive ones, they will not have a House majority.