Some states with extensive experience in using mail-in ballots have adjusted for those extra steps.
In Florida, clerks can start counting ballots 22 days before an election. In North Carolina, beginning five weeks before the election, county boards insert approved ballots into a voting machine, allowing for a prompt tabulation on Election Day.
But other states such as Michigan, Pennsylvania and Wisconsin, all with Republican-led legislatures and all of them swing states, made a conscious decision to wait so there would be no counting of mail-in ballots prior to Election Day, As a result, it could take days to tally enough ballots to project a winner.
The wrangling in the states over the use of mail-in ballots has come as President Donald Trump claims that mail voting is ripe for fraud.