For the first time in four decades, The Associated Press will be television networks' sole source for vote-counting on election night.

ABC, CBS, NBC, CNN, FOX News Channel and the AP chose to disband Voter News Service, a company created in 1964 to collect election results and conduct exit polls, following highly publicized failures in 2000 and 2002.

The news organizations created the National Election Pool (search), and contracted with two veteran pollsters to conduct exit surveys. They turned to the AP for the job of vote counting. Here's a look at some issues surrounding the AP's system.

Q: How will the vote counting be different this time for the networks?

A: In the past, the participating news organizations received raw vote numbers from both VNS and the AP, and used one as a check against the accuracy of the other. Now they will rely on the AP alone.

Q: How is the vote counted?

A: The AP has hired stringers in each of the nation's 4,600 counties, who get the results as soon as they're reported by elections boards. They call in these numbers to data collection centers, where they are entered into computers. In total, nearly 5,500 people work election night to operate this system.

Q: How can I trust that the numbers are correct?

A: If results are entered into the system that differ markedly with past elections in a county, the computer will send an alert, telling data-entry people to check with a supervisor. That happened once in a primary; one county erroneously reported that a candidate had 100,000 more votes than he actually had. So the numbers were double-checked to get the right results.

Q: What if the computer crashes or power goes out?

A: There are a number of separate computer systems. If one has trouble, another can carry the load without a loss of data.

Q: Are these employees properly trained to do the job?

A: Most have done this before. All of the data-entry personnel have been given information about the voting patterns of their particular states. So if the computers don't notice that something's wrong, they will.

Q: Sounds good in practice. What happens during the crush of election night?

A: The same system was used successfully during this year's presidential primaries. The AP also is conducting two "dress rehearsals" later this month to approximate conditions on Nov. 2. It's also not a new business for the AP; the news cooperative has collected election results since 1848.

Q: How will these numbers be used?

A: Many AP newspaper members will post them on their Web sites, and commercial sites will use them as well. Television viewers will see them reported by the networks as they come in on election night. AP political writers and bureau chiefs will use these raw numbers, as well as exit polling data, to declare winners or losers in particular races.