Boundaries are drawn inside countries too. In the United States, the 435 seats in the House of Representatives are divided among the states after each census (reapportionment), and then each state draws its districts (redistricting). The Civics course covers the rules in Apportionment and Redistricting; here we look at the geography.
Key idea
Gerrymandering is drawing district lines to give one group an advantage. Two techniques: packing (putting many of the other side's voters into a few districts, so they win those by huge margins and waste votes) and cracking (spreading the other side's voters thinly across many districts, so they fall short in each).
Why it works
With winner-take-all districts, it is not just how many votes a group has, but where its voters are counted. A vote beyond what is needed to win a district, or a vote in a district the group loses, does not add a seat. Whoever draws the lines can arrange those wasted votes. The word comes from 1812, when a Massachusetts district signed into law by Governor Elbridge Gerry was said to look like a salamander.
Worked example: Count the seats
Five districts of 100 voters each. Group A has 260 of the 500 voters, arranged as 90, 90, 30, 25, 25 in the five districts. How many districts does A win?
- A wins a district with more than 50 of its 100 voters.
- Districts with 90 and 90: A wins both. Districts with 30, 25, 25: A loses all three.
- Check the total: 90 + 90 + 30 + 25 + 25 = 260.
Answer: A wins 2 of 5 districts with 52% of the votes: A's voters were packed.
Worked example: Is an odd shape proof?
A district has a long, twisting shape. Is it gerrymandered?
- Districts must have nearly equal populations and often follow rivers, county lines, coastlines and communities.
- Any of these can make a strange shape.
- The question is the effect on representation, which needs the vote numbers, not just the outline.
Answer: Not necessarily. Shape alone does not prove it.
Common mistake
Thinking odd shapes always mean gerrymandering. Districts also follow rivers, county lines and equal-population rules; the test is the effect on representation, which courts and voters judge under the law. A neat, compact map can also favor one side.
People disagree about who should draw district lines. Some states let the legislature draw them; others use independent or bipartisan commissions. Supporters of legislatures say elected officials answer to voters; supporters of commissions say mapmakers should not draw their own districts. This course describes both views.