Is voter fraud a problem in the US?

Is voter fraud a widespread issue? I'll search for current evidence and expert assessments.

In the United States voter fraud is considered very rare, according to research and government assessments, though isolated cases do occur.

How rare?

National databases

Analysis of the Heritage database is often cited to argue rarity:

The Brennan Center for Justice, which analyzed the Heritage database, found it confirms what numerous studies have consistently shown: Voter fraud is vanishingly rare, and impersonating a voter at the polls is less common a phenomenon than being struck by lightning. Its assessment found the compilation contains very few examples of the forms of fraud most cited in policy debates — only about ten cases of in-person voter-impersonation fraud and roughly 41 cases of noncitizen voting across the period covered — numbers that are microscopic compared to billions of ballots cast.

Follow-up work by Loyola Law School's Justin Levitt found just 31 credible instances of impersonation fraud from 2000 to 2014, and a Brennan Center report determined that Americans are more likely to be struck by lightning than to commit voter-impersonation fraud.

Types of fraud

1. Voter impersonation: Voter impersonation, or in-person voter fraud, occurs when someone votes in-person under the identity of someone else. It is extremely rare. Between 1978 and 2018, no elections were overturned by courts due to voter impersonation fraud.

2. Mail-in ballot fraud: Fraud occurs more often with mailed-in votes than with in-person voting, while still being quite rare. Between 1978 and 2018, at least fourteen elections were invalidated or overturned by courts due to absentee ballot fraud, twelve of which were at the local level.

3. Noncitizen voting: Illegal voting by noncitizens occurs when noncitizens vote in elections they are not eligible to... It is extremely rare.
Studies have found very small numbers:

Official assessments

Government security agencies have found no evidence of widespread fraud affecting national outcomes:

Why the debate persists

Scholarly and legal perspectives that fraud is rare coexist with a perception gap. Policy research compiled over years consistently find voter fraud to be rare and concentrated in isolated incidents, while surveys from 2024 document that beliefs in widespread fraud remained widespread among segments of the public. False accusations of electoral fraud also have a long history, and since the 2016 and 2020 elections have often been associated with Donald Trump and the election denial movement.

Some groups, such as the Heritage Foundation, argue that with documented proof of electoral fraud in 47 states, fraud is a spanning national problem that warrants stricter election integrity measures. Critics argue the raw counts, when placed in context of hundreds of millions of ballots cast, show a minuscule rate.

In summary, available evidence indicates that while individual cases of voter fraud - including impersonation, absentee ballot fraud, and noncitizen voting - do occur and are prosecuted, they occur at rates measured in hundredths or thousandths of a percent and have not been shown to have altered the outcome of a modern federal election.