Case study gerrymandering
After Obama's election victory in 2008, a group of Republican tacticians developed a plan to increase their chances of winning congressional seats. They targeted Democrat states due to redraw their house-district boundaries, and concentrated resources to make sure Republicans could take control of the state legislature. After this, new Republican-held state legislatures changed constituency boundaries to maximise Republican success in House of Representative elections.
Political writer David Daley has shown how in various states, such as Pennsylvania, the Republican Party spent significant campaign finance to attack a small number of Democrat state politicians, giving the Republicans a majority that they used to change boundaries for that state. The impact of changing just one state seat from Democrat to Republican was enormous. In 2008, Obama won Pennsylvania and 12 Democrat congressmen won seats from this state. In 2012, Obama won again, but only five Democrats won house elections because the constituency boundaries had changed. In 2012 - the first election using the new maps - Democratic congressional candidates received 100,000 more votes than Republicans, but Republicans won 13 of the 18 seats: 51 per cent of the vote translated into just 28 per cent of the seats. Democrats won by huge margins in just five areas, but more Republicans dominated house elections, with few changes in overall voting patterns.