Counting, canvassing and audits
Election night results are unofficial. The official result comes from the canvass — a reconciliation of ballots cast against ballots counted, including provisional and lawfully-arriving mail ballots. The canvass takes days to weeks and the shift between election night and certified totals is an expected feature of it, not evidence of irregularity.
Most states now conduct post-election audits. A traditional audit rechecks a fixed percentage of precincts; a risk-limiting audit samples ballots until it reaches a statistical confidence that the reported winner is correct, examining more ballots when a contest is close and fewer when it is not.
