Where do the numbers come from in election news coverage?

It often takes days or weeks after an election for all votes to be counted so official results can be reported. During this time, news outlets will report unofficial results of the votes counted so far. To make predictions about who will win different contests before all votes have been counted, news outlets use other sources of information to predict the results of the not-yet-counted votes for election news coverage.

These predictions are largely based on five sources:

1. Unofficial results – After polls close, election officials release unofficial results from ongoing counting efforts. These unofficial vote totals are released on a rolling basis so observers know how the count is progressing.
2. Early and mail ballot totals — Election officials release the number, but not the content, of early in-person and mail votes cast before Election Day. These numbers are compared to those from past elections.
3. Exit poll results – Exit polls are optional surveys given by the news media to randomly selected voters after they have voted. Voters say who they voted for and answer other questions about the election. Their answers give the news media an idea of what the results might be.
4. Past election turnout – News outlets use information about turnout in past elections as a guide to how many total votes might be cast in the current election.
5. Population data – The census and other official resources provide information about the number of residents eligible to vote in the current election, along with other demographic information.

News outlets use these data to forecast the winner of an election, usually days or weeks before official results are completed. When outlets are sufficiently confident in their forecast to make a prediction, they may decide to “call” the race. However, a call is still an unofficial prediction by the news outlet. No election results are official until they are certified by election officials—often days or weeks after the election.

For additional information:

• Associated Press, “The AP has called winners in elections for more than 170 years. Here’s how it’s done”
• CNN, “It’s not magic, it’s math. Here’s how CNN makes election projections”
• Election Lab, “What to Expect from Early Voting in the 2024 General Election”
• NBC, “How the NBC News Decision Desk makes election calls in 2024 races”
• Vox, “How the press calls elections, explained”