How AP Calls Elections Before All The Votes Are In

How can an election be called before all the votes are counted? And how can an organization call a race if people are still waiting to vote?

The Associated Press makes its calls based on a variety of factors, and never calls a race before poll close, says David Pace, a news editor in Washington who coordinates AP election calls. If people were still voting when the call was made, they had to have been in line by the time polls closed, he said. No one new is allowed to get in line once polls close. The AP calls races based on early vote returns provided by state and county elections offices, exit polls that conducted with voters and vote results from a random sample of precincts around the state. It's a complicated process that also compares the voting history of counties to make sure results are in line with past trends.