Facebook invited the 200 million people who regularly use the site to vote on its governing documents. But it's unclear how much of a difference it will make.
However, Facebook said the vote would be binding only if 30 percent of the site's active users voted. That would be 60 million people.
More than 640,000 people have cast ballots by Thursday afternoon. Spokesman Barry Schnitt says Facebook plans to announce the results and "next steps" Friday.