In “no ID required” states like California and New York, most in‑person voters are identified by their signed affidavit and by back‑end database checks, not by presenting an ID at the polling place. Existing empirical work suggests this approach has little observable effect on aggregate turnout or election outcomes compared with states that require ID, and fraud rates appear extremely low in both settings.[1][2][3][4][5][6]

How “no ID required” works

• Voter identity is established at registration, where applicants provide personally identifying information (e.g., driver’s license number or last four of SSN) that is checked against DMV or Social Security records under federal Help America Vote Act rules.[4][7]
• The registration form is a signed affidavit under penalty of perjury attesting to eligibility (citizenship, residence, age, no disqualifying felony, etc.), and lying is a felony in California and New York.[7][8][9]
• At the polls, most voters in California and New York simply state their name and address; poll workers locate the record and the voter signs the poll book or ballot envelope so officials can compare signatures against the one on file.[2][10][1][4]

When any ID is requested

• Federal law requires certain first‑time voters who registered by mail or online without a verifiable ID number to show some form of identification (photo or non‑photo) the first time they vote in a federal election.[11][2][4]
• If these voters cannot show ID, they can usually cast a provisional or affidavit ballot; officials then verify eligibility after the election using the information on the ballot envelope and registration record.[2][4]

Qualitative impacts on elections

• Voter experience and access: Because voters are not turned away for lacking ID, the direct barrier of obtaining and carrying ID is minimized, which is especially relevant for low‑income, elderly, disabled, or highly mobile voters.[6][10][4]
• Administrative burden: Election officials focus on registration‑stage verification and signature checks rather than frontline ID inspection, shifting workload to database matching and post‑election review of questionable signatures.[10][4][11]
• Perceptions of integrity: Supporters argue that felony penalties, database checks, and signature verification provide sufficient integrity, while critics worry that absence of a polling‑place ID check may reduce public confidence even if fraud is rare.[3][5][6][7]

Quantitative impacts: turnout and fraud

• A study of Florida and Michigan, which permit ballots without ID under monitored conditions, found that at most about 0 percent of total votes were cast without ID, implying that even an extreme assumption that all such ballots were fraudulent or would be blocked would have only a minimal impact on turnout or results.[3]
• Large‑scale studies comparing states with and without voter ID requirements find no statistically significant reduction in registration or turnout overall, or for key subgroups, when ID laws are adopted, suggesting that the difference between “no ID required” and “ID required” regimes has small aggregate turnout effects.[5][6]

Quantitative impacts: election outcomes and error rates

• Because the fraction of ballots cast without ID or that would be uniquely affected by an ID rule is extremely small, simulations and empirical work find negligible shifts in overall election outcomes attributable purely to ID requirements versus signature/affidavit systems.[5][6][3]
• Signature‑based systems can generate administrative errors, such as mismatches leading to rejection of mail ballots, but these issues are tied to signature verification policy and cure procedures rather than to the presence or absence of a polling‑place ID rule.[6][10]

If you want to go deeper, the next step could be distinguishing effects within subgroup margins (e.g., homeless voters, recently naturalized citizens) in states like CA and NY and looking at rejection/cure rate data rather than just turnout.

Sources [1] Voter ID in California - Ballotpedia https://ballotpedia.org/Voter_ID_in_California [2] Voter ID in New York https://ballotpedia.org/Voter_ID_in_New_York [3] (Almost) no one votes without ID, even when they can https://www.sciencedirect.com/science/article/abs/pii/S0165176521002214 [4] Registration FAQs - OC Vote https://ocvote.gov/faqs/registration-faqs [5] New Study Confirms Voter ID Laws Don't Hurt Election ... https://www.heritage.org/election-integrity/commentary/new-study-confirms-voter-id-laws-dont-hurt-election-turnout [6] Who lacks voter identification? The electoral implications of ... https://academic.oup.com/pa/article/78/4/695/7917523 [7] Voter Registration Requirements - OC Vote https://ocvote.org/media/usa-v-page-case-no-825-cv-01370-doc-ads/voter-registration-requirements [8] New York State Voter Registration Form https://www.vote.nyc/sites/default/files/pdf/forms/voterreg/Voter_Registration_2020_English_WEB.pdf [9] NEW YORK STATE VOTER REGISTRATION FORM https://www.dc37.net/wp-content/uploads/news/headlines/pdfs/votingregistrationform.pdf [10] You Can Vote Even if You Can't Sign Your Name https://www.disabilityrightsca.org/publications/you-can-vote-even-if-you-cant-sign-your-name [11] First-Time Voters - Voter Registration & Elections - Sacramento County https://elections.saccounty.net/VotingInformation/Pages/HAVA.aspx [12] Voter Registration - California Secretary of State https://www.sos.ca.gov/administration/regulations/current-regulations/elections/voter-registration [13] Register to Vote - Sonoma County https://sonomacounty.gov/administrative-support-and-fiscal-services/registrar-of-voters/general-information/register-to-vote [14] FILLING OUT A VOTER REGISTRATION FORM https://www.nypirg.org/pubs/202109/How-to-Fill-out-VR_Sept_21.pdf [15] Voter ID Laws - National Conference of State Legislatures https://www.ncsl.org/elections-and-campaigns/voter-id