Suppose a state has 25 voters who live in a perfect grid. Sixty percent of them belong to the Blue party, and 40 percent to the Red party.
Say the state has five House seats. We need districts roughly the same size. We can draw them to fairly reflect the population: Blue gets three seats, Red gets two seats.
But what if we want to give Blue the advantage? If we draw the districts like this, Blue holds a majority in all five districts.
Now, let’s draw a map that helps the Red party. We’ll need to get creative, since it’s in the minority. But check out what happens if we draw the districts this way.
Source: Elections - nytimes.com
