During the 2020 election, the formal verification of votes within several swing states trickled in over the month of November. Many of the states called the race before the votes were formally verified, leaving many people confused as to why.
The reason for the delay primarily had to do with mail-in voting and the methods by which it is counted. When someone votes by machine, everything is automatically tracked and logged by the computer. When one votes by mail, every aspect of that needs to be handled manually — letters need to be opened, signatures verified, voting sleeves inserted into machines, etc. The unprecedented amount of mail-in votes that were submitted, mostly due to the coronavirus pandemic, bogged down the system and led to delays.
Additionally, while many states get a jump on the process, states like Pennsylvania do not permit workers to begin counting and certifying votes until Election Day. Some states, like Nevada, accepted ballots that arrived up until a week later, so long as they were postmarked on Election Day. All of these small factors combined led to the race being called roughly four days after Election Day.
