Why results shift after election night

An election-night total is a progress report. It is the ballots election officials have tabulated and published so far. The U.S. Election Assistance Commission says results reported on election night are not the final certified results, even when a display reads that every precinct has reported. “Precincts reporting” usually describes polling-place scanners. It often does not describe every mail ballot, every provisional ballot, or every curing envelope still in process.

The order of counting is a local choice constrained by state law. One county might report small precincts first. Another might report early-vote centers first. A third might hold a large city until late. If the places that report first are not a miniature of the state, the leader can change as the rest of the ballots are added. That pattern is arithmetic. It is not, by itself, evidence that a file was altered. A real discrepancy is a question for the canvass, the audit, and the courts, which compare ballots, logs, and voter lists. A lead change is not that comparison.

Three ordinary additions move totals in the days after Election Day. Timely mail ballots are accepted on the schedule the state printed. Provisional ballots are accepted or rejected one by one after workers check eligibility. Ranked-choice rounds, in states that use them, reassign ballots already cast. A runoff, where the law requires one, is a new election rather than an addition to the first count. Each of those has its own explainer in this library. They can happen in the same week.

News organizations project winners from partial counts and from their own models. A projection can be right and still not be a certificate. This site does not project. The live results page copies figures from state election-office files after polls close, and it labels a winner only when that official file does. If the file later updates, the figures on the page update. The earlier snapshot was not a promise.

Readers comparing two screenshots should check three lines: the time of the file, whether the file says the results are unofficial, and which ballots the state says are still out. A percentage with a small number of ballots counted will jump more than a percentage with most ballots counted. That is how percentages work. It is not a reason to treat the first percentage as the state’s final word.