US election: What to know as America votes

Voters were casting ballots in the United States on Tuesday. Voting kicked off in two small New Hampshire towns, which stuck to their traditional midnight start (0500 UTC).

Republican President Donald Trump faces a tough challenge from Democrat Joe Biden as he seeks a second term in the White House. Polls give Biden a strong lead nationally, but with a number of key states split down the middle, the outcome is anything but certain.

Expect record-breaking turnout

US voter turnout for presidential elections is low compared to many other countries, hovering around 55% in recent years. However, the coronavirus pandemic led many states to modify their ballot-casting rules by expanding early in-person voting and mail-in or drop-off options.

A record-breaking 91 million Americans already cast their ballots ahead of Election Day. By October 30, early voting in Texas had already exceeded the total number of ballots cast in the 2016 election. With in-person voting taking place across the country on November 3, the overall number of ballots cast in the election will likely set new records.

Read more: Which political party benefits from mail-in voting?

It matters who shows up on November 3

Despite expanded early voting due to the COVID-19 pandemic, turnout at the polls on November 3 will still play a huge role. Republicans prefer to vote in person, so the Trump campaign has said to expect a surge of his supporters at Tuesday's polls.

Early voting gives Democrats a slight edge, but Black voters, who largely lean Democratic, prefer in-person voting, and their on-the-day turnout could still be crucial to a Biden win.

Voters under 30, who made up a large portion of non-voters in 2016, appear highly mobilized this year and roughly 63% of those who definitely plan to vote tend to support Biden. Their turnout will be important.

Latino voters, a diverse bloc whose party tendencies vary, could help tip results in certain states — in either direction. Latino turnout has been lower than the US average in past votes, but a record 32 million are eligible to vote in 2020, so if they do vote, it could be decisive.

Read more: US Green Party: 'There's more at stake than getting rid of Trump'

How does the voting system work?

The US presidential election is not decided by the popular vote; instead, the winner is determined by the electoral college, a body of 538 appointed electors, or delegates, who are apportioned to each state and Washington, D.C. A candidate needs to win enough states to secure a majority of these electors — 270 — in order to win. Hitting this number is the only thing that counts.

Read more: US Electoral College: Ensuring representation or arcane filter on democracy?

The key states to watch

Because electors are not allotted to states in proportion with their population, certain states have oversized influence in a candidate's win. Some states with many electors are surefire wins to one party. But the most important states are those with significant numbers of electoral votes and close races.

These are Florida (29 electoral votes), Pennsylvania (20), Ohio (18), Michigan (16), North Carolina (15), Arizona (11), Minnesota (10) and Wisconsin (10). The race in two historically solid Republican states, Georgia (16) and Texas (38), have also gotten tighter. A Biden win in either would be a major upset and deliver Democrats a big advantage in the count to 270.  

When will we get the results?

It depends where a state is and what its rules are. The continental US covers four time zones (Alaska and Hawaii add two more). The first state polls to close will do so around 2300 UTC. The rest close over the following six hours. After a state's polls close, winner projections will be made based on exit polls and whatever ballots have been counted.

This year, the large number of mail-in voting could complicate getting official results. While some states start counting mail-in ballots before election day, others can't start until November 3. Some states have also extended the return deadline, meaning postal votes could continue to arrive for days. In states with close races, it could be these ballots that determine the winner.

Read more: What happens if there is no winner on election night?

We may not know the next president for a while

If outstanding state results mean neither candidate can secure 270 electoral votes, then the next president may not be known for days or even weeks, until all postal votes get counted. Potentially wire-thin margins of victory could also result in numerous legal cases that could further slow proceedings. There is an important deadline though: December 8, by which all state electors must be assigned to a state winner, if Congress is to accept the election results.

Other major races to watch

In addition to voting for the president, Americans are also casting votes for Congressmen and women. All 435 seats in the lower chamber of Congress, the House of Representatives, are up for election, and the Democrats are projected to maintain their majority.

Thirty-five seats are also up for election in the Republican-controlled upper chamber of Congress, the Senate, and many races are very close, so the outcome here is much more uncertain. Some currently Republican-controlled states like Arizona could go Democratic – but some Democratic-controlled ones like Alabama could go Republican. Democrats need to add four seats to their current total to take Senate control from Republicans.

Virus takes center stage

The coronavirus pandemic has emerged as a major issue for voters in the US, the country with the highest number of cases and deaths globally. Other key concerns include the economy, health care, gun rights, the environment and abortion.

Read more: US presidential election: The top 5 issues

DW's Natalie Muller contributed reporting.