U.S. Department of Commerce

Voting and Registration

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Frequently Asked Questions

What are the different universes for which the Census Bureau provides Voting and Registration estimates?
Voting-Age Population
One of the primary criteria for being eligible to vote is age. Since 1972, every state has required that eligible voters be at least 18 years of age. Thus, the voting-age population, or the 18-and-older population, is a population base often used in presenting voting statistics. The Census Bureau has historically estimated voting and registration rates using this population.

Voting-Age Citizen Population
A second criterion for voting eligibility is citizenship. In the United States, only native or naturalized citizens can legally vote in elections. While the Census Bureau has collected voting and registration data since 1964, the CPS has gathered citizenship data consistently only since 1994. Removing noncitizens decreases the voting-age population base, resulting in higher turnout rates for any given election.

Registered Population
A third criterion for voting eligibility is registration. With the exception of North Dakota, every state requires eligible voters to formally register before casting a ballot. In terms of methods and deadlines, registration procedures vary greatly from state to state.

For what levels of geography can I find voting and registration estimates?
The Census Bureau provides most estimates down to the state level. Due to sample size constraints, data are not produced at smaller geographies.

For geographies below the state level, can I obtain estimates for the Voting-Age Population or Voting-Age Citizen Population?
Yes. For estimates of the Voting-Age Population, please visit our Population Estimates Web site. For estimates of the Voting-Age Citizen Population, please access our American Community Survey data through American Factfinder.

How far back does the Census Bureau's voting and registration data go?
Data are available for every national election since 1964.

Why might the Census Bureau's voting and registration estimates differ from other data sources?
Differences between the official counts and the CPS may be a combination of an understatement of the official numbers and an overstatement in the CPS estimates. Ballots are sometimes invalidated and thrown out during the counting process and therefore do not appear in the official counts. Official vote counts also frequently do not include mismarked, unreadable, and blank ballots. Additionally, while the total number of votes cast for U.S. Representative represents the official count, voters who do not vote for this office are not included in the reported tally. Some of the error in estimating turnout in the CPS might be the result of population controls and survey coverage. Respondent misreporting is also a source of error in the CPS estimates. The definition of "official count" can provide another source of disparity. The CPS gathers information on whether respondents voted in the November election, not whether they voted for a specific office. The CPS estimates include respondents who voted in only state or local elections, but these individuals would not be included in official vote tallies based on ballots cast for a U.S. Representative.

Can these estimates tell me who an individual voted for or with which party they are affiliated?
No, the CPS Voting and Registration Supplement does not ask any questions of a partisan nature.

Source: U.S. Census Bureau | Voting and Registration |  Last Revised: October 08, 2009