When polls across the United States start closing tonight, many questions will finally be answered as Americans finish casting their ballots in this 2020 election. But two questions are on everyone's lips right now:Who will win the presidency — and when will we know?It's impossible to answer either of these questions with any certainty. All 50 states (and Washington, D.C.) administer the vote according to their own rules, with different guidelines on how to vote, how to count the vote and how to report the vote. Now that record-breaking numbers of Americans have cast their ballots early or by mail, nobody knows for sure how long it will take to get a result.But a few things seem clear. Former vice-president Joe Biden is the favourite to win the presidency and his chances look better than Hillary Clinton's did four years ago. If he wins by the margin predicted by the polls, that's likely to be fairly obvious at some point on election night.Under any other plausible scenario, however, we probably won't know the outcome for days — perhaps longer.Let's take a look at how these scenarios likely would play out.(All times below are Eastern.)7 p.m. — Biden and Trump mark their first victories * Polls close in Georgia, Indiana, Kentucky, South Carolina, Vermont and Virginia.Networks in the U.S. don't need to wait until the vote count is completed before projecting states for one candidate or the other. When the first polls of the night close, Indiana and Kentucky are likely to be projected for Trump right away, with Vermont being projected for Biden. That will give Trump 19 electoral college votes shortly after 7 p.m. against only three for Biden.Georgia, South Carolina and Virginia could take a little longer to call, however. In 2016, it took just over an hour for South Carolina to be projected for Trump by The Associated Press, while Virginia took almost four hours and Georgia nearly five. Expect that pattern to hold in this election year as observers wait even longer to call individual states due to the large number of early and mail ballots that have to be counted.7:30 p.m. — Two key swing states start reporting * Polls close in North Carolina, Ohio and West Virginia.West Virginia will be called for Trump after the polls close there, increasing his electoral college vote tally to 24. North Carolina and Ohio, however, are expected to be very close — so even if the votes there are counted quickly, it might take a nearly complete count before a winner can be projected.But the fact that we might not have a winner at this point doesn't mean that North Carolina, Ohio and Georgia won't be telling us something. Early trends in these three states could be revealing, as they are all must-wins for Trump.The first ballots to be counted in North Carolina and Ohio are likely to be friendly to the Democrats, as they will be mostly mail and/or early ballots. Once the more Republican-leaning election day ballots begin to get counted, we will start to get an idea of where these states are heading.WATCH | Across U.S., early voters met with long lines, technical issues:8 p.m. — All eyes on Florida but Pennsylvania makes us wait * Polls close in Alabama, Arkansas (at 8:30), Connecticut, Delaware, D.C., Florida, Illinois, Maine, Maryland, Massachusetts, Mississippi, Missouri, New Hampshire, New Jersey, Oklahoma, Pennsylvania, Rhode Island and Tennessee.The networks will be able to make a lot of projections at 8 p.m. or shortly thereafter: Connecticut, Delaware, Washington D.C., Illinois, Maryland, Massachusetts, New Jersey and Rhode Island for Biden and Alabama, Mississippi, Oklahoma and Tennessee for Trump. That would put the count at 75 for Biden and 57 for Trump.If the night is going well for the Republican incumbent, the networks might have seen enough by this point to call South Carolina for Trump, allowing him to close the gap on Biden with 66 electoral college votes.Arkansas's six votes at 8:30 would increase Trump's tally to 72. If Biden is having a decent night, perhaps three of Maine's four votes will be projected for him at this point, bumping him up to 78.Projections in a few other states will not be possible at this hour, however. The most important are Florida and Pennsylvania, but calls in Maine, Missouri and New Hampshire might have to wait until more votes have been tallied.Results in Pennsylvania are unlikely to be anywhere close to complete before the night is over because of the huge amount of mail and early ballots that counters will only start adding up on Tuesday morning, so don't expect a projection in this state for a few days if it is even somewhat close.Florida, on the other hand, is largely going to report results as it does in a normal election. In 2016, it took less than three hours for the Associated Press to call it for Trump. How the count goes in this state will be something to watch — it is virtually impossible to imagine a Trump re-election without it.9 p.m. — Will the Democrats widen their map into Arizona and Texas? * Polls close in Arizona, Colorado, Kansas, Louisiana, Michigan, Minnesota, Nebraska, New Mexico, New York, North Dakota, South Dakota, Texas, Wisconsin and Wyoming.At this hour, Biden will be able to add New Mexico and New York to his count, increasing his electoral college votes to 112.Kansas, Louisiana, North Dakota, South Dakota, Wyoming and most of Nebraska likely will be projected for Trump, giving him between 99 and 109 votes depending on how his night is going. That could include a call in Missouri if his numbers look good there.The networks might hold off for a little while on a call in Colorado, though it is very likely to go to Biden.Arizona and Texas, however, could be very close. Though the count there is not expected to be overly slow, a projection will take some time if these are tight races. If Biden is able to flip Arizona, he will have a very good shot at winning the presidency. If he is able to win Texas, then he is heading toward a landslide.A closer race between Biden and Trump early in the night, on the other hand, keeps Trump in the game — especially since the early returns in Arizona and Texas are likely to be Democratic-leaning. But Wisconsin could look fairly red early on, before swinging blue some time after midnight.Michigan won't be giving us complete results for days but, like Wisconsin and Pennsylvania, it could start out leaning more Republican.10 p.m. — Iowa and Nevada start counting as trends start getting clearer * Polls close in Iowa, Montana, Nevada and Utah.By this point, some of the trends will be emerging and some of the bigger, swingier states might be approaching projections — unless the race is very close. Florida and Ohio were called in the 10 p.m. hour in 2016, so if one candidate has a decent lead over the other that could be apparent by now. If it is tight, these states might not be called for a few more hours.Virginia and Colorado should be projected for Biden by this point, while Missouri and Utah go to Trump. That puts the electoral count at 134 for Biden and 115 for Trump.We's still a long way from the 270 needed to win at this point. Iowa, Nevada and (if it's close) Montana might take some time before a call can be made.11 p.m. — West coast swings for Biden, but is it enough? * Polls close in California, Idaho, Oregon and Washington.This is a big hour for the Democrats. Though California and Washington can take a very long time to count ballots in the best of circumstances, they (along with Oregon) will be projected for Biden at this point, with Idaho going for Trump.That's a big boost in the electoral college vote for Biden. If the night is going well for him, New Hampshire and Minnesota might also be called in his favour by now, boosting his vote to 222, with Trump well behind at 119.If the night is not going well for Biden, the networks might be holding off on a call in Minnesota and could instead be calling states like Georgia, Texas and Florida for Trump. That would be a turning point in the night for the president, as a win in Florida and Georgia would open up a path back to the White House for him.But even if all of these were called for him, Trump would still be at just 205 electoral college votes.After midnight — Time to decide whether you want to stay up for this * Polls close in Hawaii (midnight) and Alaska (1 a.m.).After midnight, the pattern of the evening might be obvious. At that point, either Biden is putting up strong numbers in uncalled states and is on track for a win, or the election could be headed for a waiting game as the tally in Michigan and Pennsylvania is finalized in the days to come.Hawaii will be called for Biden at this point and, if he is having a good night, Florida and North Carolina might be called or about to be called for him as well. That would put him at 270 electoral college votes and make him the projected winner. If the calls are coming a little more slowly, then it could be a few more hours before he technically crosses that finish line — with lots of swing states yet to be called one way or the other.The question is, do you want to stay awake long enough to see how these states turn out?If the night is going Trump's way, you might as well head to bed. Even if states like North Carolina and Ohio are called for him — nudging him ahead of Biden in the electoral college count — too many other states would remain uncalled (and uncallable) for Trump to get to 270.By morning, final calls might be made in all but the closest states and those that will take days to report final results, like Pennsylvania and Michigan. If Biden is winning, he probably doesn't need these. If Trump is still in the running, then it will come down to the results in these states.WATCH | What happens if Trump rejects U.S. election results?The morning (or days) after — Either it's all over, or it's just beginningBiden and Trump both have paths to the presidency, but they're very different. Biden's is clear enough and wide enough to get him to 270 electoral college votes before the sun rises on Wednesday. Trump's path, however, runs almost exclusively through states that might not have enough votes counted before the end of the week to make a call — particularly if it's close.As in 2016, a Trump victory in 2020 likely would be due to a very close election. In such a close election, where the margins in a number of swing states are less than two points, it might not be possible to call important states like Georgia, North Carolina, Texas, Arizona or Florida.If it does get to that point, either candidate could narrowly come out on top — but it might take days to find out which one.That could mean a busy few days and weeks for vote counters. And judging by America's history with contested elections and the statements from President Trump and his team, the lawyers would be kept busy as well.