The states that are the closest aren't necessarily the ones that will take the longest to post results. For example, Georgia may be one of the most highly contested swing states this year, but on election night it may have results relatively quickly because of investments it has made in processing equipment, and a state law that allows processing of mailed ballots beginning 15 days before the election.
Pennsylvania, by contrast, won't be reporting results as fast, even if the winner's margin of victory ends up being wider. Pennsylvania voters have requested 2.9 million mailed-in ballots. But officials there won't be able to count ballots, or even process them, until Election Day. The Keystone State is seen by many forecasters to be the most likely tipping point in the 2020 election, and that's why we're being told to be patient and get ready for a Nov. 3 map with a lot of states that are neither red nor blue.