What are the Brennan Center and other nonpartisan estimates of how many voters lack matching citizenship documents?
Executive summary
The Brennan Center’s most recent collaborative national survey estimates that roughly 9.1 percent of U.S. citizens of voting age — about 21.3 million people — lack ready access to a document proving citizenship (birth certificate, passport, naturalization or citizenship certificate) if asked to produce one on short notice [1]. That figure echoes earlier Brennan Center work that found about 7 percent without easy access nearly two decades ago and is supplemented by the survey’s estimate that roughly 3.8 million adult citizens have no such documentation at all [2] [3].
1. What the Brennan Center found and how it measured it
The 9.1 percent / 21.3 million estimate comes from a survey conducted for the Brennan Center in partnership with VoteRiders, Public Wise, and the University of Maryland Center for Democracy and Civic Engagement; the poll was administered by SSRS to 2,386 U.S. citizens 18 and older and asked whether respondents could quickly locate documentary proof of citizenship [1]. The Brennan Center frames the finding as evidence that documentary proof-of-citizenship requirements for voter registration would create significant barriers, and it highlights racial disparities in access — 11 percent of American citizens of color versus 8 percent of white citizens of voting age lack ready access [1] [2].
2. Historical context: the 7 percent benchmark and continuity
The new estimate is presented as consistent with the Brennan Center’s earlier work: a 2006 study found about 7 percent of Americans didn’t have proof-of-citizenship documents readily available, a baseline the organization cites to show this is a long‑standing problem rather than a one‑off survey artifact [2]. The Center’s broader research program on voter ID and proof-of-citizenship has repeatedly argued that requiring underlying documents like birth certificates imposes time, cost, and logistical burdens that can suppress turnout [4] [5].
3. Additional numeric findings cited by the Brennan Center
Beyond the headline 21.3 million, the Brennan Center’s analysis reports that approximately 3.8 million adult citizens lack any documentary proof of citizenship at all — meaning the documents do not exist for them — a figure the Center uses to underline that some obstacles cannot be resolved simply by better outreach [3]. The organization also quantifies the racial gap and notes the practical friction of having documents locked in safety deposit boxes or difficult-to-reach offices, which the Center argues depresses registration and participation [2] [4].
4. Other nonpartisan estimates and competing evidence — what’s missing and what’s agreed
Most of the sources provided are Brennan Center reports or coverage of its survey; independent nonpartisan work cited by the Center and others has consistently found that actual voting by noncitizens is vanishingly rare, which frames the policy debate — critics of proof-of-citizenship measures argue the burdens outweigh any marginal fraud prevention benefit [6] [7]. The search set does not include a competing national, nonpartisan estimate that directly contradicts the 21.3 million figure; where debate exists it centers on methods, interpretation and the tradeoff between preventing potential noncitizen voting and the risk of disenfranchising citizens [8] [5].
5. Caveats, criticisms and what the data do not settle
The Brennan Center’s estimate rests on a single recent national survey of a few thousand respondents and on definitional choices about “ready access,” so it is subject to standard polling limitations — sampling, question wording, and respondents’ interpretation of “readily available” [1]. Critics of other related studies (not specifically this one) have challenged survey design and interpretation in the past, and the Brennan Center acknowledges that implementation details of state laws and administrative practices will shape how many people are actually excluded if proof-of-citizenship rules are imposed [8] [9]. The sources provided do not offer an independent national calculation that invalidates the Brennan Center’s 9.1 percent estimate; they do, however, provide robust context showing that even conservative reviews find noncitizen voting uncommon, intensifying the policy question about whether document rules are a proportionate response [6] [7].