The Citizen’s Checklist for Evaluating Redistricting Maps

Every ten years, following the national census, states redraw congressional and state legislative district boundaries to reflect population changes. The process, formally called redistricting and informally sometimes called gerrymandering when done to favor a particular outcome, produces maps that most citizens never examine closely despite how directly those maps shape political representation for a decade. The following checklist offers a neutral framework for evaluating any map, regardless of which party drew it.

1. Population Equality

Under the “one person, one vote” principle established by the Supreme Court in the 1960s, congressional districts within a state must have nearly identical populations, typically within a fraction of a percent of each other. Check whether the map’s district populations deviate significantly from the state’s average district size; large deviations can indicate a map was drawn with less rigor or potentially manipulated for partisan advantage, since population imbalance is one of the few redistricting criteria with a very low legal tolerance.

2. Compactness

Compactness measures how geographically regular a district’s shape is, as opposed to sprawling, oddly fingered shapes that stretch across a state to connect distant pockets of favorable voters. Several mathematical scores exist to quantify this, including the Polsby-Popper score, which compares a district’s area to the area of a circle with the same perimeter. A low compactness score is not automatically illegal, since some irregular shapes follow natural geographic features like rivers or coastlines, but unusually convoluted districts deserve closer scrutiny.

3. Contiguity

A contiguous district is one where every part of the district is connected; a resident should be able to travel from any point in the district to any other point without leaving the district’s boundaries. Nearly all state constitutions and most state redistricting statutes require contiguity, making this one of the more straightforward criteria to verify simply by examining a map directly.

4. Preservation of Communities of Interest

Many state redistricting criteria call for keeping existing communities, whether defined by shared economic interests, cultural ties, or local government boundaries like counties and cities, intact within a single district rather than splitting them apart. This criterion is more subjective than population equality or contiguity, since “community of interest” is not always precisely defined in law, but unusually frequent splitting of cities, counties, or recognized neighborhoods across multiple districts is a reasonable flag.

5. Compliance with the Voting Rights Act

Section 2 of the Voting Rights Act prohibits district maps that dilute the voting power of racial or language minority groups, which has produced a body of case law requiring careful analysis of whether a minority community that could otherwise form a majority in a single district has instead been divided among several districts where it cannot elect a candidate of its choice, or “packed” into one district at an unnecessarily high concentration. Evaluating this criterion properly generally requires detailed demographic data rather than visual inspection alone.

6. The Efficiency Gap and Other Partisan Fairness Metrics

The efficiency gap is a statistical measure developed by political scientists to estimate how many votes each party “wastes,” either through losses in districts they had no chance of winning or through votes beyond what was needed in districts they won comfortably. A large efficiency gap favoring one party across a state’s full map is one signal, among several, that a map may have been drawn to maximize one party’s seat share disproportionate to its statewide vote share. No single metric is considered definitive by courts or scholars, and different metrics sometimes disagree, which is why analysts typically look at several measures together.

7. Transparency of the Drawing Process

Finally, consider how the map was actually produced: through an independent or bipartisan redistricting commission, a state legislature controlled by one party, or a court-ordered process following a legal challenge to a prior map. States vary considerably in this structure, and the process itself is a meaningful indicator of how much partisan input shaped the final lines, independent of any specific geometric or statistical measure.

Checklist Summary

Using the Checklist Responsibly

No single criterion on this list proves a map is unfair on its own, and courts evaluating redistricting challenges typically weigh several of these factors together rather than relying on any one measure. The goal of this checklist is not to render a verdict on any specific state’s map, but to give readers a structured, repeatable way to ask informed questions the next time a new congressional map is unveiled in their state.

Where to Find the Underlying Data Yourself

Most of the raw material needed to apply this checklist is publicly available, though it requires some patience to locate. State redistricting commissions or legislative committees typically publish proposed maps along with shapefiles, the geographic data format that allows mapping software to calculate compactness scores and population figures directly. Many state election offices also publish precinct-level results from recent elections, which independent analysts and academic researchers use to calculate statewide partisan fairness metrics like the efficiency gap. Several nonpartisan academic and civic organizations publish accessible, plain-language analyses of proposed maps using this same public data, which can be a useful starting point for readers who want the underlying numbers without building the calculations themselves.

How Redistricting Authority Varies by State

Not every state redraws its congressional map the same way. Some states assign the task to the state legislature directly, subject to the governor’s veto power in most cases, while a growing number of states have adopted independent or bipartisan redistricting commissions specifically designed to reduce single-party control over the process. A handful of states use hybrid models combining legislative input with advisory commission review. Because the structure varies so significantly from state to state, checking which specific model a given state uses is itself a useful first step before evaluating any particular map, since the degree of built-in partisan insulation differs considerably depending on which body actually holds final drawing authority.