vote and not voting twice. and in some states votes are counted even if they come in days after the election, as long as they are postmarked by election day. and eight states don't even start looking at the mail-in ballots until election day. pennsylvania, for one, is going to take a long time. more than 2 million ballots in the state have been returned, and they won't even start processing them until election day. >> i feel confident that the overwhelming majority will be counted by friday, if not before. >> reporter: but that doesn't mean we won't know who won the presidency earlier than that. it depends on how close the race is. in several key states, states donald trump must win, the counting is expected to happen quickly. florida, georgia, and arizona, for example, are among the states where most or nearly all of the votes are expected to be in by election night. in florida, they have been processing ballots for over a month. and with more than half of registered floridians voting early, we could have a very good