What is a voter file?
A voter file is an official record of every registered voter in a given jurisdiction – your city council district, school board zone, state legislative district, or other electoral geography. It is maintained by your local or state elections office (typically called the Board of Elections, County Clerk, or Registrar of Voters) and updated continuously as people register, move, or are removed from the rolls.
Every registered voter has a record in the file. Depending on your state, that record typically includes:
- Full name and residential address
- Date of birth
- Date of voter registration
- Party registration (in states with partisan registration)
- Precinct assignment
- Phone number (where available)
- Email address (where collected by the elections office)
- Vote history – a record of which elections the person has voted in, which party's primary ballot they chose (if applicable), and sometimes by what method (e.g. in person, early, or absentee/mail)
What a voter file does NOT include
A voter file records whether someone voted in a given election – not who they voted for. That information is secret by law and is never part of the voter file.
How to get a voter file
You have two main options: purchase directly from your local elections office, or purchase from a commercial data vendor. Each has trade-offs worth understanding before you decide.
| Local elections office | Commercial data vendor | |
|---|---|---|
| Cost | Free to a few hundred dollars | Hundreds to thousands of dollars |
| Format | Often raw spreadsheets that require cleanup | Cleaned and ready for database software |
| Data quality | Contact information can be incomplete or out of date | More accurate, with additional data points |
| Extra data | Standard fields only | Inferred party, phone, email, consumer overlays, issue relevance scores |
| Best for | Small local races with a tight budget | Larger races where richer data improves targeting, smaller races with sufficient budget |
From your local elections office
Your local elections office is required by law to make the voter file available to candidates. Contact them (either in person, by phone, or via their website) to request the file for your district. You'll typically pay a nominal fee, often a few cents per record or a flat fee ranging from free to a few hundred dollars, depending on the jurisdiction and the size of the file.
The main advantage of going directly to the elections office is cost, as it's almost always the least expensive option. With the lower cost, though, comes some limitations. First is format: files from elections offices are often raw spreadsheets that require cleanup before they can be imported into database software. The second is quality: contact information included in the basic voter file can be incomplete or out of date (with bad phone numbers a particularly common problem).
From a data vendor
Commercial voter data vendors purchase, clean, and enhance voter files from elections offices around the country. Their files are typically more accurate, in more usable formats, and enriched with additional data points: inferred party affiliation for non-partisan registration states, phone numbers, email addresses, issue relevance scores, and sometimes even consumer data overlays that provide additional context on voter interests and demographics.
The trade-off is cost. Vendor files are typically more expensive than buying from the elections office – often hundreds to thousands of dollars depending on the district size and the level of data enrichment. For a small local race with a tight budget, the elections office file may be sufficient. For larger races where the richer data set would meaningfully improve targeting – or smaller races with sufficient budget – a vendor file is worth the investment.
Why vote history is the most important part
Here's a fact that surprises many first-time candidates: most registered voters don't vote in most elections.
Presidential elections bring out the highest share of registered voters – typically 55–65% in competitive states. But turnout in local races, off-year elections, and non-presidential primaries drops dramatically. A city council race in an odd year might see turnout of 10–20% of registered voters. A school board race can be lower still.
Consider what this means in practice. Suppose your district has 10,000 registered voters:
Of 10,000 registered voters
Unless you have unlimited time and resources, you can't realistically engage all 10,000 registered voters before election day, and trying to do so means spending time on people who are very unlikely to show up. Vote history lets you focus on likely voters: the people who have actually voted in comparable past elections. Concentrating your outreach on this group is the single biggest efficiency gain available to any campaign.
How to build your target voter universe
Your target voter universe is the group of voters you will prioritize for outreach. It starts with the voter file, filtered for likely voters based on vote history.
Define "likely voter" for your race
The right definition of a likely voter depends on the type of race you're running. For most local races, a good starting point is voters who participated in both of the following:
- A recent comparable local election (a city council, school board, or municipal race from a similar election cycle), and
- A recent high-turnout election (such as a presidential or major statewide election)
Voters who show up in both categories are demonstrating consistent voting behavior across different types of elections. They're your core target universe.
The specific elections you choose should depend on your district and the office you're seeking. Use your judgment to select the most relevant comparable elections from the past four to six years – typically the two most recent cycles that most closely resemble your race.
Your universe must be larger than your vote goal
This is critical: your target universe needs to be meaningfully larger than the number of votes you need to win. Not every voter you contact will vote for you, and not every voter you try to contact will be reachable. A universe that's only slightly larger than your vote goal leaves no room for error.
If your criteria are producing a universe that's too small, loosen them to include more elections, extend the time window, or lower the threshold for vote frequency.
Learn how to calculate your vote goal →
A note on party registration
In states with partisan voter registration, party affiliation is an obvious filter for partisan campaigns. But registration data has limits. In non-partisan registration states, the file won't include party affiliation – though it will often show which party's primary ballot a voter requested, which is a useful proxy. And in local races generally, party registration predicts behavior less reliably than it does in federal elections.
How to map your voter universe
Once you've filtered your voter file down to a target universe, plot it on a map.
Most campaign software will let you visualize voter data geographically. Looking at where your likely voters live helps you:
- Plan canvassing routes efficiently, prioritizing dense, walkable areas to maximize contacts per hour
- Identify neighborhoods where your support is likely to be strongest
- Spot demographic patterns that might affect your messaging or language needs
- Determine which precincts to prioritize with your volunteer time
Your precinct-by-precinct breakdown is especially useful here. Precincts are the smallest geographic unit of electoral politics – roughly neighborhood-sized. Every voter file includes precinct assignments, and knowing which precincts have the highest concentrations of likely supporters helps you allocate your resources strategically.
For demographic context beyond what the voter file provides, the U.S. Census Bureau's data tools are a useful supplement, particularly for larger districts where understanding the socioeconomic and linguistic makeup of different neighborhoods matters for outreach planning.
What software do you need?
The voter file is typically delivered as a spreadsheet. For the smallest races, you can work with it in Excel or Google Sheets, filtering rows by vote history columns, sorting by precinct, and so on. It's manageable, though time-consuming.
For most campaigns, dedicated software makes voter file management significantly more efficient. A good platform will let you:
- Import your voter file and automatically build individual voter records
- Filter for likely voters using vote history fields without writing formulas
- Visualize your universe on an interactive map
- Assign voter lists to individual canvassers and volunteers
- Record the results of every voter contact in real time, keeping your data current throughout the campaign
- Merge records from multiple sources (volunteer lists, donor records, event signups) into unified supporter profiles
Platforms like NationBuilder are designed specifically for these workflows, making your voter file usable for essential campaign tasks from day one rather than requiring spreadsheet cleanup.
Next steps
Once you have your voter file and have built your target universe, you're ready to:
- Build your contact plan – the schedule and methods for reaching voters at each stage of the campaign
- Begin recruiting volunteers and contacting voters