We settle the market for the US presidential election based on the result declared by the Press Association. They will declare a result once one of the candidates has the required number of 270 electoral college votes. You can check their latest news feed here. Please note that some news sites may have different vote counts dependent on when they project a candidate to have sufficient votes to win a State.
The result of the US election can be disputed and historically there have been legal challenges over who has won which can go on for a considerable amount of time after election day. As we want to settle our bets and payout customer winnings as quickly as possible, we settle bets as soon as a result is declared by the Press Association. This means that any subsequent legal challenges or amendments to the result will not be taken into account.