A turnout rate is a fraction. The numerator is a count of ballots. The denominator is a population. When the two are mismatched, the rate is wrong, and the chart that carries it is wrong in a way that looks precise.
The most common version of this error is not arithmetic. It is a labeling failure. A chart says “turnout of the voting-age population” when the underlying survey estimate is actually of citizens. The number is real. The label is not.
What the Census Bureau actually says
The Census Bureau’s voting and registration pages are explicit about the base for their visualization estimates. On the participation visualizations, the Bureau states: “Estimates are based on the citizen voting-age population, which is anyone age 18 and older who is also a citizen.”
That sentence is the whole argument. The Bureau’s own charts do not use the voting-age population as the denominator. They use the citizen voting-age population.
The distinction matters because the two populations are not the same size. The voting-age population includes everyone 18 and older. The citizen voting-age population excludes noncitizens. Same numerator, larger denominator, smaller rate. A chart that swaps the labels without swapping the math will overstate the base and understate the rate.
The 2024 figures, read carefully
The Census Bureau’s April 30, 2025 release of the 2024 voting and registration tables reported that “in the 2024 presidential election, 73.6% of the voting-age population was registered to vote and 65.3% voted.”
Read that sentence twice. The Bureau’s summary language uses “voting-age population” in the headline sentence, while its visualization pages describe the estimates as based on the citizen voting-age population. The two are not interchangeable, and a chart builder who grabs the first phrase and ignores the second will mislabel the base.
The safe move is to attribute the figure to the source that produced it. If the number comes from the CPS voting supplement, say so. If the denominator is the citizen voting-age population, say that. If the Bureau’s summary sentence uses a shorter phrase, do not treat the shorter phrase as the technical definition.
Where the numbers come from
The Current Population Survey is the instrument behind these estimates. The Census Bureau describes the CPS as “sponsored jointly by the U.S. Census Bureau and the U.S. Bureau of Labor Statistics (BLS)” and as “the primary source of labor force statistics for the population of the United States.” The voting supplement rides on that survey.
The Bureau has collected data on the characteristics of American voters “for every national election since 1964.” The P20 detailed tables are released every two years following national level elections. That cadence matters for chart builders: the series is biennial, not annual, and the supplement is a survey, not a vote count.
Survey estimates and administrative counts are different animals. A survey estimate of who voted carries sampling error and relies on self-report. An administrative count of ballots cast carries its own coverage problems. Neither is wrong. They answer different questions, and they do not share a denominator by default.
The denominator distinction in plain terms
Three populations are commonly confused in turnout charts:
- Voting-age population (VAP): everyone 18 and older, including noncitizens and, depending on the series, people barred from voting by state law.
- Citizen voting-age population (CVAP): citizens 18 and older. This is the base the Census Bureau’s voting visualizations describe.
- Voting-eligible population (VEP): a further-adjusted base that removes noncitizens and, in some constructions, ineligible felons and other barred groups. This is the concept the United States Elections Project builds its estimates around, and it is not the same as either Census series.
The same numerator over VAP and over CVAP produces two different rates. The gap is not a rounding artifact. It is the size of the excluded population, expressed as a rate difference.
This post does not put a number on that gap. The retrieved Census pages do not publish a side-by-side VAP and CVAP turnout series for the same election, and the P20 detailed tables did not retrieve for this draft. The direction of the effect is certain from the definitions. The magnitude is not established here, and a chart that asserts a magnitude without a source is doing something the source does not support.
Why the label is the fix
The repair is editorial, not statistical. You do not need to recompute anything. You need to name the denominator in the chart.
Put the base in the title or subtitle. “Turnout among the citizen voting-age population, 2024” is a different claim from “turnout, 2024.” The first can be checked against the source. The second cannot, because it does not say what it is a rate of.
Name the survey. A CPS voting supplement estimate and an administrative count are not substitutes. If the chart mixes them across years, the line is not a trend. It is a change in method drawn as a change in behavior.
Name the year and the release. The P20 tables are revised and re-released. A figure pulled from a 2021 release and a figure pulled from a 2025 release may not be the same series.
A worked example of the labeling failure
Suppose a chart plots a single bar labeled “2024 turnout: 65.3%.” The number traces to the Census Bureau’s 2024 release. The label does not say whose turnout.
Now suppose the same chart’s subtitle reads “share of the voting-age population.” The number is now attached to a base the Bureau’s visualization pages do not use for that estimate. The bar height is unchanged. The claim is changed.
The correction is one line of text: “65.3% of the citizen voting-age population voted, per the Census Bureau’s 2024 voting and registration tables.” That sentence is checkable. The original is not.
Comparing across years and places
Before plotting two turnout series on one axis, confirm that both use the same denominator definition. A series built on VAP and a series built on CVAP will not meet cleanly at the join, and the discontinuity will read as a real change in turnout.
The same caution applies across states. Eligibility rules differ. Felony disenfranchisement rules differ. A state-level turnout map that uses one denominator for all states is making a comparability assumption that the underlying eligibility rules may not support.
None of this means state comparisons are impossible. It means the denominator has to be stated, and the reader has to be told what was held constant and what was not.
Rule of thumb
Before you label a turnout rate, find the sentence in the source that defines the base. If the source says “citizen voting-age population,” label it that way. If the source says “voting-age population,” label it that way. If the source says “voting-eligible population,” label it that way and cite the methodology that produced it.
Do not translate between the three. They are not synonyms, and the chart’s credibility rests on the reader being able to match your label to the source’s definition.
A short checklist for the next headline chart
- Name the denominator: VAP, CVAP, or VEP.
- Name the survey or count: CPS voting supplement, administrative tally, or other.
- Name the year and the release the figure came from.
- If two series share an axis, confirm both use the same denominator definition.
- If the source’s own summary language is looser than its methodology page, follow the methodology page.
FAQ
Is the Census Bureau’s 65.3% figure for 2024 a VAP rate or a CVAP rate?
The Bureau’s release sentence uses “voting-age population,” while its voting visualization pages describe their estimates as based on the citizen voting-age population. The two phrases are not interchangeable. Attribute the figure to the release and quote the Bureau’s own wording rather than paraphrasing it into a different denominator.
Does the EAC or FEC publish a turnout rate I can use instead?
The retrieved EAC and FEC pages do not address turnout rate denominators. The EAC’s Election Administration and Voting Survey covers registration and election administration topics; the FEC’s data pages cover campaign finance. Neither is a substitute for the CPS voting supplement on this question.
How large is the gap between VAP and CVAP turnout?
This post does not state a magnitude. The retrieved sources do not publish a side-by-side series, and the P20 detailed tables did not retrieve for this draft. The direction is determined by the definitions; the size requires a source that this draft does not have.
Can I compare a CPS turnout estimate to an administrative ballot count?
Only with care. They have different numerators and different coverage properties. A chart that plots them on one axis without saying so is presenting a method change as a behavior change.
Sources
- U.S. Census Bureau, Voting and Registration topic page, including the 2024 release note and the visualization descriptions of the citizen voting-age population base: https://www.census.gov/topics/public-sector/voting.html
- U.S. Census Bureau, Current Population Survey program page, including the joint Census-BLS sponsorship: https://www.census.gov/programs-surveys/cps.html
- U.S. Election Assistance Commission, Studies and Reports, for EAVS scope and coverage: https://www.eac.gov/research-and-data/studies-and-reports