Republican presidential nominee Donald Trump cast today his vote in Manhattan, he was accompanied by his wife Melania Trump. 
Democratic Presidential nominee Hillary Clinton had cast her vote at an earlier time today, Chappaqua, New York. 
The American president is indirectly elected through what is called an Electoral College votes. The total number of those Electoral College votes are 538. The candidate who gets the most votes at any state automatically wins all the Electoral College votes there. 
The American constitution says that the US Congress shall choose the President in case there was Electoral College tie.

Source: QNA