Joe Biden becomes the 46th President of the United States of America after taking Pennsylvania. He becomes the next president, pending any legal challenges.
Biden has won the crucial state, giving him 20 electoral college votes, bringing his total to 273 and surpassing the 270 needed to win the election.
Under the US system, voters in each state pick electors, who then gather a few weeks after the election to decide the winner. Each elector equals one electoral vote, and the number of electoral votes per state is roughly in line with its population – so bigger states like Texas (38) and California (55) have more, while smaller states like Delaware (3) and Idaho (4) have fewer. In total there are 538 electoral votes, and a candidate needs 270 to win.
Pennsylvania was enough to get Biden over that halfway line. With leads in Georgia, Arizona and Nevada, he may well end up winning far more than needed – taking those three states would give him a total of 306.