Four scenarios: How U.S. election night may play out

The final day of voting in the United States has arrived and attention has switched to election night: How could the evening play out for Donald Trump and Joe Biden?

Several factors have combined to make election night in the United States particularly uncertain in 2020: A massive increase in early and mail voting has changed how and when ballots will be counted; there is expected to be record turnout; the specter of 2016 and Trump's surprise win has hovered over a polling picture that in previous years would have told a clear story; and the expectation that neither candidate will easily concede has sowed seeds of doubt.

For all of these reasons, it's hard to say when the results of the presidential or congressional races will be known. It'll vary from state to state, with each having different rules, and with lawyers from both parties poised to jump in once voting ends, the uncertainty could last for days.

Here are four possible scenarios to watch out for in the hours after the polls close.

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