Gerrymandering Explained: How to Read the Maps

Gerrymandering is the manipulation of election district boundaries to favor a particular party or candidate. Every ten years, after the census, states redraw congressional and state legislative maps to reflect population changes. Whoever controls that drawing can shape who wins for a decade — and, increasingly, can redraw mid-cycle too. The core techniques are simple enough to spot once you know them. Cracking splits a group of disfavored voters across several districts so they are too small a share to win anywhere. Packing does the opposite: it crams disfavored voters into as few districts as possible, where they win by huge margins but waste votes that could matter elsewhere. Map drawers often use both at once. Where did the word come from? The name is a two-century-old accident. In 1812, Massachusetts Governor Elbridge Gerry approved redrawn districts designed to keep his party in power.

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