Voter turnout

Voter turnout is a measure of how many people turn out to vote. Because high voter turnout is considered a vital mark of a thriving democracy, policymakers and citizens often support electoral reform measures based on whether they will increase turnout, either overall or for particular groups.

Although the idea of voter turnout is simple, measuring it is complicated. And even if the number of people who voted in an election is accurately counted, it's often unclear what turnout should be compared to—the number of eligible voters? Registered voters?

There have been many political debates over whether particular reforms will raise or lower turnout. During the 2020 election cycle, for example, there was ample discourse about the potential effects of election administration reforms enacted in response to the COVID-19 pandemic. 

Turnout can be measured in the aggregate by simply counting the number of voters who participated in an election. Data from the University of Florida (UF) Election Lab indicates that nearly 156.8 million voters cast ballots in the 2024 presidential election. It has historically been difficult to determine the number of ballots cast because many states have not included the total number of ballots cast in their election results. This meant that researchers had to use the number of votes cast for the highest-level office on the ballot that year (e.g., U.S. President or U.S. Senate) to measure turnout in a state. However, more and more states are now reporting the total number of ballots counted alongside their election results. According to the UF Election Lab, only a few states reported presidential votes as their official measure of turnout for the 2024 election; most states reported total ballots cast.

While the number of ballots cast provides insight into how many people voted, it does not indicate the share of potential voters who actually turned out. With the number of voters determined, we need a denominator in order to calculate the turnout rate. Often, states and news sources use voter registration totals as the denominator when providing turnout numbers. This results in varying measurements across states due to inconsistent practices, policies, and/or laws around the maintenance of their voter registration lists. For a more consistent measure of the turnout rate, it is better to use a denominator that reflects the population of eligible voters.

The easiest comparison is with the voting-age population (VAP)—that is, the number of people aged 18 and older, according to the U.S. Census Bureau. However, the VAP includes individuals who are ineligible to vote, such as non-citizens and those disfranchised because of felony convictions. Thus, two additional measures of the voting-eligible population have been developed:

• Citizen Voting Age Population (CVAP), which is based on Census Bureau population estimates generated using the American Community Survey.
• Voting Eligible Population (VEP), which is calculated by removing felons (according to state law), non-citizens, and those judged mentally incapacitated.

The denominator that one chooses for calculating the turnout rate depends on the purposes of the analysis and the availability of data. Usually, VEP is the most preferred denominator, followed by CVAP, and then VAP. The estimated VEP in 2024 was 243.8 million, compared to an estimated VAP of 264.8 million.

The graph below shows the nationwide turnout rate in federal elections, calculated as a percentage of VEP, from 1980 to 2024, as reported by the UF Election Lab. In addition to the variation over time, the most notable pattern in this graph is the difference in turnout between years with presidential elections ("on years") and those without ("off years"). Elections held in odd-numbered years and at times other than November typically have significantly lower turnout rates than those shown on the graph. The turnout rate in the 2020 presidential election was the greatest since 1904.

Sometimes we want to measure turnout rates for specific groups of voters or study the factors that lead individual citizens to vote. In these cases, we need individual measures of turnout based on answers to public opinion surveys.

The primary difficulty in using public opinion surveys to ascertain individual voter turnout is social desirability bias: respondents who did not vote may claim they did to be perceived more favorably by others. As a result, estimates of turnout rates from surveys will be higher than those from administrative records. (For example, 75% of respondents to the 2024 American National Election Studies survey reported voting, compared to the actual turnout rate of 64% as reflected in the first figure above.) To guard against over-reporting turnout in surveys, some studies use voter registration records to independently verify whether respondents voted, but the difficulty and expense of obtaining these records means that few take this step.

Even with the problems of over-reporting, public opinion surveys are usually the only way we can study turnout patterns among voter subpopulations, such as regional or racial groups. It would be safe to use these surveys if all groups over-report voting at similar rates, but evidence suggests that isn’t the case.

One consequence of the secret ballot is the inability to directly tie demographic factors to an actually recorded vote. Instead, researchers have relied on the Voting and Registration Supplement (VRS) of the U.S. Census Bureau’s Current Population Survey (CPS) to gather information about the demographic factors that affect turnout. The CPS is a monthly survey on employment and the economy. The VRS, which is administered every November in even-numbered years, asks respondents whether they voted in the most recent election. Because the CPS already has a rich set of demographic information about each voter and has been conducted for decades, this is often the best source of data.

The dominant theory of why turnout varies focuses on a cost-benefit analysis from the voter's perspective. Voters compare what they stand to gain if one candidate beats another against the economic and social costs of casting a ballot. Other scholarship builds on this approach by theorizing that the intrinsic reward of fulfilling one’s civic duty to vote also factors into a voter’s decision to turn out.

A long history of political science research has shown that the following demographic factors are associated with higher voter turnout: greater education, higher income, older age, and being married. Women currently vote at slightly higher levels than men.

Can particular election reforms, such as Election Day registration (EDR), vote-by-mail, early voting, photo ID, etc., affect voter turnout? Research results for most of these areas have been mixed. The one reform that is most consistently correlated with higher levels of turnout is Election Day registration, although there is disagreement over whether EDR causes higher turnout, or if states with existing higher turnout levels are more likely to pass EDR laws, or whether (most likely) it’s a combination of the two.

What about the roles that campaigns play in stimulating voter turnout? This is most visible in presidential elections, where candidates pour disproportionate resources into campaigning in battleground states—those that are closely divided along partisan lines and thus most likely to swing the Electoral College vote. In 2024, the average turnout in the eight states where the presidential margin of victory was five percentage points or less was 72%, compared to 61% in the nine states where the margin of victory was greater than 30 points. (For the states in-between, the average turnout rate was 65%.)

Field experiments testing the effects of campaign communications on voter turnout have shown that personalized methods are most effective at mobilizing voters, whereas mass e-mails are rarely effective at stimulating turnout.

We care about turnout for two reasons. First, higher turnout is considered an indicator of a well-functioning democracy. Second, if we believe that lower turnout levels exclude citizens with particular political views, then increasing turnout would “unskew” the electorate.

Early research did not find evidence that increasing turnout in federal elections would radically change the mix of opinions among those who actually vote. However, more recent research suggests that voters in national elections are more likely to be Republican and to oppose redistributive social policies than non-voters. Differences between voters and non-voters on other issues, such as foreign policy, are much less pronounced.

When it comes to off-cycle elections, overall turnout rates tend to be much lower than elections held to coincide with federal elections, and the demographic characteristics of voters are much more skewed compared to non-voters.

Data Sources

American National Election Studies

The United States Election Project

U.S. Census Bureau—Voting and Registration

Suggested Readings

Aldrich, John H. 1993. "Rational Choice and Turnout." American Journal of Political Science 37 (1): 246–278.

Green, Donald P., and Alan S Gerber. 2015. Get Out the Vote: How to Increase Voter Turnout. Washington D.C.: Brookings Institution Press.

Hur, Aram and Christopher H. Achen. 2013. “Coding Voter Turnout Responses in the Current Population Survey.” Public Opinion Quarterly 77(4); 985 – 993.

Leighley, Jan E., and Nagler, Jonathan. 2013. Who Votes Now?: Demographics, Issues, Inequality, and Turnout in the United States. Princeton: Princeton University Press.

Silver, Brian D., Barbara A. Anderson, and Paul. R. Abramson. 1986. "Who Overreports Voting?" American Political Science Review 80 (2): 613–624.

Riker, William H.,  and Peter C. Ordeshook. 1968. "A Theory of the Calculus of Voting." American Political Science Review 62 (1): 25–42.

Wolfinger, Raymond E.,  and Steven J. Rosenstone. 1980. Who Votes? New Haven: Yale University Press.