Blue shift

In American politics, a blue shift, also called a red mirage, is an observed phenomenon under which counts of in-person votes are more likely than overall vote counts to be for the Republican Party (whose party color is red), while provisional ballots or absentee ballots, which are often counted later, are more likely than overall vote counts to be for the Democratic Party (whose color is blue). This means that election day results can initially indicate a Republican is ahead, but adding provisional ballots and absentee ballots into the count can eventually show a Democratic victory.

Confusion about the blue shift phenomenon has led some Republicans to call the legitimacy of elections into question when, in fact, the election results were legitimate. Blue shift occurs because young voters, low-income voters, and voters who relocate often are likely both to vote provisionally and to lean Democratic. This phenomenon remains poorly understood by the general public and election experts, and can cause confusion given that Americans are accustomed to learning projected results on election day and often assume the projected results announced then are an accurate representation of final results.