Explore Your Voter Power

Research

General information about Americans Together data sitewide. 

Americans Together maps are built to make sense of a complex and constantly shifting U.S. election system. While no central source tracks the full picture, we’ve synthesized data from dozens of reputable sources to provide a comprehensive, nonpartisan view of elections at the national, state, and district level. Given the evolving nature of election law and reporting, our maps reflect the best available information as of publication—and we welcome your feedback. Kindly email info@americanstogether.com.

Section 1: Voter Power Index Methodology

The Voter Power Index (VPI) is made up of three components: 

  • Competitiveness trend score
  • Structural score
  • Party affiliation score

The final Voter Power Index score is a weighted 60/25/15 average of the competitiveness trend score + the structural score + the party affiliation score. 

The scores are indexed to a nominal benchmark of 50, meaning that a value of 50 represents the overall average of the dataset. Indexing the scores allows for a standard benchmark across a range of different datasets. A VPI score above 50 is greater than the national average. A VPI score of 100 represents twice the national average.

Part 1. Competitiveness Trend Score:

2020 and 2024 Presidential Margins (calculated independently)

  • The calculations place higher values on the most competitive races. Using a 100-point scale, a 0-point margin scores 100, and a 100-point margin scores 0. 
  • Bonuses are added for split ticket districts (where voters choose presidential and congressional winners from different parties) 
  • Example: In an election whose margin was 55% to 45%, the margin score would be 90 (100-raw margin). A split ticket would bump this score up to 95 (as the average of the margin plus a 100 split ticket bonus). The calculated score is indexed against the national average (50).

2020, 2022, and 2024 House Margins (calculated independently)

  • The calculations place higher values on the most competitive races. Using a 100-point scale, a 0-point margin scores 100, and a 100-point margin scores 0. 
  • Bonuses are added for seats that flipped parties from the prior election.  
  • Example: In an election whose margin was 55% to 45%, the margin score would be 90 (100-raw margin). A flipped seat would bump this score up to 95 (as the average of the margin plus a 100 split ticket bonus). The calculated score is indexed against the national average (50).

For State scores, the competitiveness score uses 2020 and 2024 statewide presidential results and 2020, 2022, and 2024 Senate results in lieu of district level House races.  Some states did not have Senate elections all three years. State scores don’t factor in split tickets or flips.

Voter Turnout (2020 & 2024): 

The calculations place higher values on elections where the percentage of voters in the primary is closest to the percentage who vote in the general election. Using a 100 point scale, elections where the same percentage of voters vote in the primary and general election the score is 100. The 2020 and 2024 scores are averaged and indexed to a mean of 50.

Part 2: Structural Score:

The structural score measures your district’s election rules and voting systems and assigns a score based on how fair or unfair they are. Can independents vote in primary elections?  Do candidates need a majority to win an election? Who drew your district boundaries? The more fair and open your district’s elections, the higher its structural score. The below three values are averaged together to come up with one overall average structural score. The results are then indexed to a benchmark mean at 50.

  • The general election score: Plurality=0, Majority plus top 2 runoff=25, Majority plus runoff=50, Top 2 majority=75, Top 4 majority plus runoff=100
  • The gerrymandering score:  State drawn maps=0, Advisory commissions=50, IRC=100
  • A primary type score: Closed=0, Varies by Party=25 (Closed and Semi-closed or Closed and Semi-closed), Semi-closed=50, Open=75, Nonpartisan=100

Part 3. Party Affiliation Score

The Party Affiliation Score (PAS) measures both the size of the unaffiliated voter group and how much leverage unaffiliated voters have in their state or district.  

The PAS captures the joint presence of two conditions that make a district’s electorate persuadable: balanced partisan registration and a meaningful share of unaffiliated voters. Both must be present for the score to be high — a strong showing on one cannot compensate for the absence of the other.

Where U% is small or one party dominates registration, one party can win on its base alone, meaning unaffiliated voters have no power.

Formula:

Party Affiliation Score = (*Partisan balance / 100)^0.4 × (*Unaff% / 100)^0.6 × 100

*Partisan balance = (1 − |Rep% − Dem%| / 100) × 100. Higher when major-party registration is closely split.

*Unaff% = share of registered voters with no party affiliation.

  • Weighting: Unaffiliated share is the primary signal (exponent 0.6); partisan balance is secondary (exponent 0.4). The exponents sum to 1, making this a weighted geometric mean.
  • Indexing: PAS is indexed to a mean of 50 across all districts before entering the VPI composite, so 50 represents the average district and 100 represents twice the average.

What does the party affiliation formula do?  

The PAS inputs are joint requirements. The composite inputs are separate signals.

The PAS inputs are raw percentages with meaningful zeros. If partisan balance = 0, this means a district is 100% one party (no balance whatsoever).  If Unaff% = 0 means literally no unaffiliated voters in the district. Both zeros correspond to real conditions, and the multiplicative form says “if either condition is fully absent, the joint signal is absent.” 

Multiplication has a property addition doesn’t: if either factor is near zero, the product is near zero, no matter how big the other factor is.

The strong partisan balance can’t rescue the formula from the very low unaffiliated share, since multiplying anything by a small number gives a small result. That’s the mathematical way to model the joint-precondition behavior of partisan balance and high unaffiliated percentage.

The Voter Power score then takes the indexed overall competitiveness score and multiplies it by 60%. Then it takes the indexed overall average structural score and multiplies it by 25%. Then it takes the indexed overall average party affiliation score and multiplies it by 15%. The sum of these three values is the Voter Power score.

VPI Sources:

    Section 2: Primaries

    The Primaries map uses a number of different sources to determine primary types in each state. Primary systems are varied and nuanced in each state. Many states use different types of primary elections for different offices. When questions arose, we cross-referenced with local sources to determine primary election information. Relying only on public data paints an incomplete picture. Voter registration percentages are unavailable for many states and districts. These percentages constantly change and states which do register voters by party report affiliation percentages at different intervals.  We purchased party affiliation percentages at the time of the 2024 general election for every state and congressional district from a third party data provider.

    Main Source: https://ballotpedia.org/Primary_election_types_by_state

      Section 3: General Elections

      Voting systems in each state can be found at: https://ballotpedia.org/Electoral_systems_by_state

      Section 4: Gerrymandering

      Redistricting processes in each state can be found at: https://gerrymander.princeton.edu/reforms

      Section 5: Competitive Races

      2024 House Race Results: https://ballotpedia.org/Election_results,_2022:_Congressional_margin_of_victory_analysis

      Section 6: Primary Voter Turnout

      For the Primary Voter Turnout map, we purchased 2024 voter turnout data and voter registration data from a third party data provider for every state and congressional district. The data reflects voter registration and turnout at the time of the 2024 general election. We also looked at which states held separate congressional and presidential primaries. We relied mainly on state election websites to see where dates differed for congressional and presidential primary elections.

      Section 7: Term Limits

      Term limits for governor and state legislatures can be found at:

      Section 8: Partisan Control

      For single party control and state government trifectas: https://ballotpedia.org/State_government_trifectas

      For specific composition of state legislatures: https://ballotpedia.org/Historical_partisan_composition_of_state_legislatures#2024_Elections

      For supermajorities:https://ballotpedia.org/Veto_overrides_in_state_legislatures

      23 states with single party control in 2008: https://ballotpedia.org/State_government_trifectas#trifectastatus-2010-15