It’s that time again.

Americans head to the polls on Tuesday to elect a president, as they do every four years on the day after the first Monday of November.

There are also plenty of down-ballot votes, including Congressional races, 11 governorships, other state- and local-level elections, and ballot questions – think referendums – in some states.

But for Americans and outside observers alike, the presidential race is the biggest one of them all.

CTVNews.ca has compiled a guide to the presidential election for Canadians and others who are interested in following election night, but haven’t been paying attention until now and may not be familiar with the American electoral system.

Read on to find out how the president is chosen, which issues have dominated this year’s campaign and when results are expected to come in.

WHO IS RUNNING FOR PRESIDENT?

It’s a race between two men for whom the White House is familiar territory: Donald Trump and Joe Biden.

Republican nominee Trump is the incumbent president, having won the last election in 2016. Democratic nominee Biden was vice-president under Barack Obama from 2008 through 2016.

However, they are not the only choices for voters. Many third-party and independent candidates will be on the ballot in one or more states, led by Libertarian Party nominee Jo Jorgensen, who will be an option in every state.

While not generally a major factor in presidential elections, independent and third-party candidates did garner more than five per cent of the popular vote in 2016.

The most recent presidential candidate from outside the two main parties to attract significant support is Ross Perot, the Texas billionaire who won nearly 19 per cent of the popular vote in 1992 and more than 8 per cent in 1996.

HOW IS A WINNER DETERMINED?

Although the names of Trump and Biden will appear on ballots across the U.S., votes don’t directly decide the presidency.

Instead, voters are picking the candidate they want their state’s electors, or delegates, to endorse. Those delegates – the famed “electoral college” – then meet in their states and determine the result of the presidential election.

The electoral college system has shifted since its formation, so that almost all delegates now endorse whichever candidate received the most votes in their state. This means that the candidate who garners the most votes in Texas, for example, gets all 38 of the state’s electoral votes, no matter how slim the margin is between them and the runner-up.

The only exceptions to this are Nebraska and Maine, which award some of their delegates based on results from local districts.

States are awarded electoral votes based on the number of representatives they have in the House of Representative and Senate. This means that the distribution of electoral votes is mostly population based, with some bias in favour of less-populated states, as House seats are allocated based on population while the Senate is comprised of exactly two members from each state.

There are a total of 538 electoral votes, leaving 270 as the magic number to win more than 50 per cent – and thus, the presidency.

Because of this system, it is possible for a candidate to win the election despite receiving fewer votes than their main opponent. This has only happened four times in 58 presidential elections, although two of them were recent – in 2000 and 2016.

That said, it would be hypocritical for Canadians to gloat about this bizarre quirk of the U.S. system. After all, Andrew Scheer never became prime minister despite his Conservative Party winning the popular vote in our last federal election.

WHICH STATES MATTER MOST?

Because the presidency is decided by the electoral college and different states have different levels of representation in that body, some states carry much more weight than others.

And because of the winner-take-all stakes of the college, “battleground” or “swing” states where both parties have strong support are seen as much more important for achieving victory than “safe” states that always vote the same way.

That’s why Michigan, Pennsylvania and other swing states traditionally see far more visits from prospective presidents during American campaigns than those that traditionally vote for the Democrats, such as New York and California, or those that traditionally vote for the Republicans, such as Georgia and Arizona. Winning those latter states is to be expected. Winning the swing states means winning the White House.

Every election cycle, strategists for both parties identify various paths to victory and focus their campaigns on ensuring the right number of votes in enough states to reach 270 electoral college votes.

Key battlegrounds this time around include many of the usual suspects, including Florida, Pennsylvania, Wisconsin and Michigan. Those tracking the polls closely say a number of seats normally considered safe for the Republicans could flip – potentially even Texas, which would signal a seismic shift in American electoral politics.

WHEN WILL WE KNOW WHO WON?

It’s hard to say.

For one thing, when the polls close is decided on the state level. States that span multiple time zones may even have separate voting end times for residents of each time zone.

Polls close in all but 10 states by 9 p.m. EST, although voters who are in line when the voting day ends are still eligible to cast their ballots. Some results will likely be public knowledge before this point.

Typically, a winner is declared in presidential elections during the late-night hours. If the race is especially close, it might happen after most Americans have gone to bed.

But this isn’t a typical election. Between the large turnout for advance voting, the expected high levels of mail-in ballots, and the possibility of a disputed result, it’s entirely plausible that the result won’t be evident on Tuesday, or on Wednesday, or on many days thereafter.

The worst-case scenario, at least for those hoping for a speedy resolution, is a repeat of what happened in 2000. That year, the outcome of the election went all the way to the U.S. Supreme Court, which ordered on Dec. 12 that a recount in Florida be stopped.

The electoral college is mandated by the U.S. Constitution to award their votes on the second Wednesday in December. This year, that’s Dec. 14.

WHEN DOES THE WINNER BECOME PRESIDENT?

No matter when it is determined who won Tuesday’s election, the winner will be sworn in on Jan. 20, 2021.

WHAT WILL IT MEAN FOR CANADA?

The U.S. is Canada’s closest neighbour and largest trading partner, so even the slightest shift in its political winds can have a major effect on this country.

Prime Minister Justin Trudeau said last month that his government is “going to be prepared for various eventualities” following the vote.

CTVNews.ca has taken in-depth looks at how either a Biden victory or a second term of Trump could affect Canada when it comes to trade, relations with China, defence and other foreign policy files, climate change, immigration and the oil and gas industry.

HOW CAN I FOLLOW ALONG?

CTV's Chief News Anchor and Senior Editor Lisa LaFlamme leads THE AMERICAN ELECTION 2020 special, with in-depth live coverage beginning at 7 p.m. ET on CTV News Channel and 8 p.m. ET on CTV.

Canadians can also access up-to-the-minute results and historic moments throughout the evening via CTV’s digital and social media platforms, including CTVNews.ca, the CTV News app, and @CTVNews on Twitter.

Visitors to CTVNews.ca can follow the campaign on our America Votes hub, join our dedicated Facebook group and get the latest numbers from our poll tracker.

WHAT ELSE SHOULD I KNOW?

Here is some further reading to get you up to speed before election night: