US House Redistricting
When redistricting is enabled, US House elections resolve per congressional district instead of statewide proportional allocation. Each district has its own lean derived from a 16-square voter map; a party holding a state trifecta (governor plus chamber majority from the same party) can redraw that map between cycles.
District Maps
Each state's House delegation is represented as N districts × 16 squares. Every square is tagged left, right, or grey (swing). District lean comes from the square mix — a district heavy on right squares is safer for Republicans; packed left or right squares create lopsided seats.
House races in a redistricted state run one election per district. Candidates compete for a single seat using the same vote-accumulation engine as other races, but the underlying electorate is the district's lean, not the whole state average.
Who Can Draw Maps
Map authority depends on state legislation (three policy levers):
| Law | Options | Effect |
|---|---|---|
| Redistricting authority | Independent commission / Bipartisan commission / Legislature-drawn | Only legislature-drawn maps can be gerrymandered by the trifecta holder; commissions block partisan draws |
| Compactness | Strict / Moderate / Loose | Caps how far any district's lean may deviate from the state mean |
| Fairness | Strict / Moderate / Loose | Caps the statewide efficiency gap — a measure of wasted votes across districts |
A trifecta (same party controls the governorship and the state legislature majority) is required to open the map editor in legislature-drawn states.
Drawing Rules
Proposed maps must satisfy all active caps:
- Each district totals exactly 16 squares (no negative counts).
- Statewide square totals are conserved — you redistribute voters, not invent them.
- Per-district deviation — no district may lean more than the compactness tier allows away from the state mean.
- Packed districts — districts with ≥12 squares of one color count toward a packed-district limit.
- Efficiency gap — the statewide gap between wasted left and wasted right votes must stay below the fairness ceiling.
Illegal maps cannot be saved. Auto-map presets respect the same legality checks — strategies blocked by current law are disabled in the UI.
Map Editor Tools
Trifecta holders use the state redistricting editor to:
- Drag squares between districts manually.
- Apply auto-map strategies (maximize seats, neutralize, protect incumbents, etc.) within legal caps.
- Review a composition summary — seat lean breakdown, compactness indicators, and efficiency-gap readout before committing.
Committed maps take effect for the next House cycle in that state.
Campaign Effects
District-level races mean ground game and ads target a smaller electorate. Statewide popularity still matters, but winning a gerrymandered map often requires contesting the handful of grey or lightly leaning districts rather than running up margins everywhere.
Related
- Election Mechanics — Vote accumulation and FPTP resolution
- General Elections — Closing-sprint tactics at district scale
- Demographics — How state texture feeds district leans
- Bills & Legislation — State redistricting, compactness, and fairness laws