How are the results reported US Elections?
The election results are reported by the Associated Press (AP). AP announces the winner in a state when they determine that the opponent candidate has no chance to win. This can be done before 100% of vote count in a state have been counted.
Estimates for the total vote in each state are also provided by Associated Press. The numbers update throughout election night, as more data on voter turnout becomes available.
A candidate needs to win 270 electoral college votes (50% plus one) to win the election.
The winner of the election is determined through a system called the electoral college. Each of the 50 states, plus Washington DC, is given a number of electoral college votes, adding up to a total of 538 votes. More populous states get more electoral college votes than smaller ones.
In every state except two – Maine and Nebraska – the candidate that gets the most votes wins all of the state’s electoral college votes.
Due to these rules, a candidate can win the election without getting the most votes at the national level. This happened at the last election, in which Donald Trump won a majority of electoral college votes although more people voted for Hillary Clinton across the US. sources
The credit of this information is to The Guardian.com.