"Josh Mendelsohn, CEO of the Democratic data firm Hawkfish, has warned of an election-day 'red mirage' of victory for Mr. Trump, which will be replaced in short order by a 'blue shift'..."

"...as the outstanding, heavily Democratic mail ballots are counted. Such a dramatic change from the election-night result could lead to baseless Republican charges of fraud and cries that the election was rigged, which could spark dangerous political unrest. These nightmare scenarios ignore several key facts, however. Most states begin processing their ballots before election day, and almost all begin putting them through scanners before the polls close. Many states intermingle sent-by-mail and election-day ballots at the polling places, where they are scanned together, so that when the precinct count is released, it contains both in-person and mail ballots. In such states—which include such battlegrounds as New Hampshire and most of Wisconsin—the polling place counts may be released a few hours later than they might in another year, but not days later. More generally, local jurisdictions have been preparing all summer for a surge in mail ballots; most will be counted on election day in parallel with the day’s in-person ballots, so that the results of many ballots cast in advance can be announced early on election night."

From "Actually, We Will Know a Lot on Election Night/Most states begin processing their presidential ballots before Nov. 3, and local officials have been preparing all summer for a surge in mail ballots" (Wall Street Journal).