Understanding how VoteValue works and where our data comes from
Data freshness
VoteValue uses authoritative data sources to provide comprehensive voting district information with 100% real precinct data coverage across all 50 states plus DC.
January 2026: VoteValue now has complete nationwide coverage using VEST 2020 precinct data from Harvard Dataverse. All 51 states (50 states + DC) have real, certified 2020 Presidential election results at the precinct level with true precinct boundaries and 100% vote conservation.
163,904 precincts with 156,144,718 actual votes from official state election authorities.
The VoteValue Index quantifies voting power on a 0-100 scale by analyzing five key factors that determine how much impact your individual vote has in shaping electoral outcomes.
How close recent elections have been, based on margin closeness, historical volatility, and party-flip frequency. Data from MIT Election Lab, MEDSL, and Princeton/Klarner historical archives.
Room for increased turnout to shift outcomes. Based on turnout gap vs. national median and whether the race is contested. Data from election results and Census ACS voting-eligible population.
How much one vote can swing the result. Based on absolute vote differential and district population size. Smaller districts with closer margins give each voter more structural weight.
How fairly the district is drawn. Combines geometric compactness (Polsby-Popper, Reock, Convex Hull from Census TIGER shapefiles) with partisan efficiency gap analysis (Stephanopoulos & McGhee 2015).
How much this race matters for shifting chamber control. Based on chamber partisan margin (from OpenStates), contestedness, and incumbency vulnerability.
The VVI is a linear weighted sum of the five subscores, each normalized to [0, 1]:
VVI = 100 Γ (0.35 Γ competitiveness + 0.20 Γ mobilization + 0.15 Γ leverage + 0.20 Γ integrity + 0.10 Γ significance)
No nonlinear scaling or score inflation is applied. A score of 72 means the weighted average of normalized metrics is 0.72.
All district boundaries are sourced from the U.S. Census Bureau's TIGER/Line Shapefiles, the official geographic database for U.S. political boundaries.
| Data Type | Source | Year | Update Frequency |
|---|---|---|---|
| Congressional Districts | Census TIGER/Line (CD) | 2024 (119th Congress) | After redistricting |
| State Senate Districts | Census TIGER/Line (SLDU) | 2024 | After redistricting |
| State House Districts | Census TIGER/Line (SLDL) | 2024 | After redistricting |
| Voting Precincts (VTDs) | Census TIGER/Line (VTD) | 2020 | Decennial Census |
Raw shapefiles are converted to GeoJSON format and simplified for web performance (tolerance: 0.0005Β°) while preserving district boundary accuracy. Coordinates use WGS84 (EPSG:4326).
All 51 states (50 states + DC) now have real, certified 2020 Presidential election results at the precinct level from the VEST (Voting and Election Science Team) dataset hosted by Harvard Dataverse.
VEST (Voting and Election Science Team) compiles official, certified election results from state election authorities and matches them to true precinct boundaries. This is the gold standard for precinct-level election data.
Data Quality: 100% vote conservation (source data, no estimation or distribution), true precinct boundaries (not VTD approximations), official results verified by state election authorities.
| Geographic Level | Coverage | Data Source | Data Type |
|---|---|---|---|
| Precincts | 51/51 States | VEST 2020 (Harvard Dataverse) | Real Votes - 100% Conservation |
| β³ Precinct Count | 163,904 precincts | Certified state election results | 156,144,718 votes |
| β³ Fields Included | dem_votes, rep_votes, total_votes, margin, dem_pct, rep_pct, turnout | ||
| β³ Metadata | data_source: "VEST 2020", is_estimated: false, election_year: 2020 |
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The precinct service uses the following priority cascade when loading data for a state:
1. VEST 2020 (Primary) β Used for all 51 states β
2. NY Times Upshot 2020 (Fallback) β Not needed, VEST covers all states
3. State-specific sources (Fallback) β Not needed, VEST covers all states
4. OpenPrecincts (Fallback) β Not needed, VEST covers all states
5. Census VTD boundaries only (Last resort) β Geometry only, no partisan data
All 51 states: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming
Margin = (Democratic % - Republican %) of two-party vote
Positive values indicate Democratic lean (D+X), negative values indicate Republican lean (R+X).
Example: A precinct with 60% Democratic and 40% Republican has a margin of +20 (D+20).
Using the real VEST precinct data as a foundation, we can derive partisan data for finer and coarser geographic levels through spatial analysis.
Census blocks are the finest geographic unit (~11 million blocks nationwide), but the Census Bureau does not collect vote data at this level. We distribute VEST precinct votes to census blocks using population-weighted spatial overlay:
Step 1: Spatially overlay precinct boundaries with census block boundaries to identify intersections
Step 2: For each precinct, sum the 2020 Census population of all intersecting blocks
Step 3: Distribute votes proportionally by population:
block.dem_votes = precinct.dem_votes Γ (block.POP20 / precinct_total_pop)
block.rep_votes = precinct.rep_votes Γ (block.POP20 / precinct_total_pop)
Validation: Vote conservation within 0.0-2.0% of precinct totals
Availability: Census block data can be generated for any state with VEST precinct data (currently available for 13 states, can be expanded to all 51).
Metadata: is_estimated: true, data_source: "VEST 2020 (population-weighted distribution)", distribution_method: "population"
District-level partisan data is calculated by aggregating VEST precinct votes that fall within each district boundary using area-weighted spatial overlay:
Step 1: For each district, identify all VEST precincts that intersect the district boundary
Step 2: Calculate the overlap area ratio for each intersecting precinct:
area_ratio = (precinct β© district area) / total_precinct_area
Step 3: Aggregate votes using area weights:
district.dem_votes = Ξ£ (precinct.dem_votes Γ area_ratio)
district.rep_votes = Ξ£ (precinct.rep_votes Γ area_ratio)
Step 4: Calculate margin and percentages from aggregated totals
Validation: Vote conservation within 0.01% for all states
Availability: District partisan data can be generated for any state with VEST precinct data (currently available for 13 states, can be expanded to all 51).
Metadata: is_estimated: false (real votes, spatially aggregated), data_source: "VEST 2020 (precinct aggregation)", vote_source_method: "area_weighted", coverage_pct
| Level | States Processed | Processing Status |
|---|---|---|
| Precincts (VEST 2020) | 51/51 | Complete - All States |
| Census Blocks (derived) | 13/51 | Partial - Can expand to all 51 |
| Congressional Districts (derived) | 13/51 | Partial - Can expand to all 51 |
| State Senate (derived) | 13/51 | Partial - Can expand to all 51 |
| State House (derived) | 13/51 | Partial - Can expand to all 51 |
Compactness measures how efficiently shaped a district is. Irregular, sprawling shapes may indicate gerrymandering.
Compactness = 4Ο Γ Area / PerimeterΒ²
Score ranges from 0 to 1 (displayed as 0-100%), where 100% is a perfect circle. Lower scores may indicate gerrymandering.
| Score Range | Rating | Interpretation |
|---|---|---|
| β₯ 40% | Compact | Regular, efficient shape |
| 25-40% | Moderate | Some irregularity, often follows natural features |
| 15-25% | Irregular | Unusual shape, may warrant scrutiny |
| < 15% | Potentially Gerrymandered | Highly irregular, likely intentionally drawn |
Primary source for precinct-level 2020 Presidential election results. Covers all 51 states (50 states + DC) with certified results from state election authorities. Maintained by the Voting and Election Science Team.
Congressional election returns spanning nearly five decades. Used for competitiveness scoring, margin history, volatility, and party-flip frequency in the VVI Competitiveness metric.
Statewide Senate election returns. Used for Senate race competitiveness and historical margin trends.
County-level presidential election returns. Used for geographic partisan context and turnout analysis.
2022 midterm Senate results at county level.
Precinct-level 2022 Senate results.
Historical state senate election results used for margin volatility and competitiveness trends in the VVI.
Historical state house election results. Used alongside Klarner data for multi-decade competitiveness analysis at the state legislative level.
2022 midterm results aggregated at precinct and district level. Supplements Princeton/Klarner archives with the most recent state legislative election cycle.
Official geographic boundaries for the 119th Congress: congressional districts (CD119), state senate (SLDU), and state house (SLDL). Also 2020 Voting Tabulation Districts (VTD). Used for district geometry, point-in-polygon lookups, and compactness metrics.
Census block population data used for population-weighted distribution of precinct votes to census blocks.
Population, education, and income estimates by geography. Used for voting-eligible population calculations.
State-level voting-eligible population by year (Michael P. McDonald). Used for turnout elasticity in the VVI Mobilization Potential metric.
State legislative representative data, district assignments, and chamber composition (party seat counts). Used for representative lookups and the VVI Race Significance metric.
Geocoding and place data for address-to-coordinates conversion.
These sources were evaluated but are not currently used in production since VEST 2020 provides complete coverage:
A machine-readable BibTeX file with complete citations for all datasets is available in the repository at
CITATIONS.bib.
If you use VoteValue or its data outputs in academic work, please cite the original data providers.
| Data Type | Current Version | Last Updated | Next Expected Update |
|---|---|---|---|
| VEST Precinct Partisan Data | 2020 Presidential | January 2026 (51/51 states) | When VEST 2024 dataset released |
| β³ Data Source | Certified state election results from November 2020 - 163,904 precincts, 156M votes | ||
| Congressional District Boundaries | 119th Congress (2024) | January 2024 | After 2030 Census redistricting |
| State Legislative Boundaries | 2023 redistricting | January 2024 | After 2030 Census redistricting |
| Precinct Boundaries (VEST) | 2020 (true precincts) | November 2020 | When VEST 2024 released |
| Census Block Boundaries | 2020 Census (TABBLOCK20) | 2020 | 2030 Census |
| Census Block Partisan Data (derived) | 13 states processed | January 2026 | Can expand to all 51 states |
| District Partisan Data (derived) | 13 states processed | January 2026 | Can expand to all 51 states |
Future Update: VEST typically releases new precinct data 6-12 months after an election. The VEST 2024 dataset is expected in late 2025 or early 2026. When released, VoteValue will update to include 2024 Presidential election results.
Page last updated: April 4, 2026
Major Update: Achieved 100% nationwide precinct data coverage (51/51 states) using VEST 2020 dataset
Data compiled from authoritative public sources