Voter File

A voter file (also called a voter registration file or voter roll) is the official list of individuals registered to vote within a given jurisdiction, maintained by election authorities. In the United States, voter files are typically compiled at the state or county level under statutes such as the National Voter Registration Act of 1993 ("Motor Voter Act") and the Help America Vote Act of 2002, which require states to maintain a single, centralized, computerized voter registration database.

Core fields usually include the voter's name, residential address, date of birth, registration date, party affiliation (in states with partisan registration), and a vote history flag indicating whether the person voted in past elections — not how they voted, since the ballot remains secret. Some files also include phone numbers, gender, and assigned precinct or districts.

Voter files serve several functions:

• Administrative: poll books, mail-ballot dispatch, signature verification, and list maintenance (removing deceased or relocated voters).
• Political: campaigns purchase or license the file and append commercial and modeled data — turnout scores, partisanship scores, issue propensities — to build targeting universes for canvassing, phone banking, and direct mail. In the US, vendors such as the Democratic Party's DNC voter file, the Republican GOP Data Center, NGP VAN, i360, TargetSmart, and L2 dominate this market.
• Research: academics and journalists use voter files to study turnout, redistricting effects, and demographic representation.

Access rules vary widely. Some US states (e.g., Ohio, North Carolina, Florida) make the file broadly available; others restrict use to political or non-commercial purposes, or charge significant fees. Outside the US, practice differs sharply: the UK maintains an electoral register with an "open" and "full" version, while many European countries derive voter lists from population registers and tightly restrict campaign access under GDPR.

Voter files are distinct from ballots, census data, and citizenship rolls, though list maintenance disputes — such as purges — frequently intersect with all three.