London — US presidential elections are not won by the national popular vote. The winner in each state collects its electoral college votes – and needs a total of 270 to take the White House.

In most elections the result is clear – although not officially confirmed – by the end of the night. Major American media outlets “call” each state for one of the candidates. While not based on the final vote count, that projection is almost invariably accurate.

This means an accurate tally of electoral college votes can be made and a winner declared. In 2016, that happened at 2.30am in Washington when Trump reached the required 270.

The states that could decide this year’s race. Trump’s victories in Florida, Ohio and Texas have kept alive his hopes of re-election, but a key state, Arizona, has been called for Biden. If the Democratic challenger wins Michigan and Wisconsin, he could afford to lose Georgia and Pennsylvania and still win the election by two electoral college votes.

Compare 2016 result with 2020