AP’s David Scott talks about how the newsroom predicts who won, the ‘red mirage’, and one county’s whiteboard

The way the US counts votes is unique. In fact, there is no one central vote-counting system but rather tens of thousands of them in local precincts all across the country.

To help determine who has won where, the Guardian and many other newsrooms rely on the Associated Press, which has been calling US elections since 1848. (Some television networks, such as CNN, use their own analysis of results to make race calls.)