The presidential election doesn't end when the polls close on 8 November. Rather, it's just getting started.
Once the votes are counted, the state-by-state process kicks in. The Electoral College meets in mid-December to vote, and Congress makes the results official in January.
A look at how the President is elected:
The vote, by universal suffrage, is conducted in a single round in all 50 states and the District of Columbia (the city of Washington, which is not part of any state).
Most people who voted early or are heading to the polls on 8 November think they will be voting for Democrat Hillary Clinton, Republican Donald Trump or their chosen third-party candidate. But they won't be. They'll be voting for their state's electors, who will in turn cast votes for the presidential candidate who wins the most votes in their state.
Each state has as many electoral votes as it has members of Congress. The District of Columbia has an additional three electors.
There are a total of 538 electors in the Electoral College, with the number from each state based on its population size.
A state has one elector for each of its members of the House of Representatives, and one for each of the state's two senators.
California — the most populous state — therefore has 55 electors, Texas has 38, and New York and Florida have 29 each. At the other end of the spectrum, lightly populated Alaska, Delaware, Vermont and Wyoming have only three electors each, as does the District of Columbia.
The overall winner must take half of that plus one — or 270 electoral votes.
Power to the states
Electors are chosen by each party, and typically are party insiders who can be trusted to vote for their candidate. Members of Congress can't be electors, by law.
An elector has only one duty — to elect a president.
While it may seem like a complicated system, the Electoral College was created by the 12th Amendment of the Constitution to empower the role of individual states.
"It's the states that decide who the President is and not the general population as a whole," says Miriam Vincent, a staff attorney at the National Archives, which acts as a liaison between the states and Congress during the electoral college process.
19 December — The real election day
By law, the electors must meet on the first Monday after the second Wednesday in December. This year, that's 19 December.
On that day, they gather in their respective states to cast votes for President and Vice-President of the United States.
In almost every state, the winner of the state's popular vote gets all of the state's electors. Maine and Nebraska are exceptions, where two electors are chosen by popular state-wide vote and the remainder are chosen according to the popular vote in each congressional district.
The winner-takes-all system in the states makes it extremely hard for a third-party candidate to prevail, although they can still have critical impacts on certain states and therefore on the national result.
There's nothing in the Constitution that says the electors are required to vote for a particular candidate, and state laws vary. But according to the National Archives, 99 percent of electors through US history have voted for their party's candidate, and none of the dissenters — known as "faithless electors" — has ever changed the result of an election.
Once the votes have taken place, each state sends its results to Washington, where they are received by the Senate and the National Archives.
Some states historically support the Democratic candidate election after election, while others are just as resolutely Republican. Candidates thus concentrate their efforts on about a dozen states prone to shift back and forth between the parties, often determining the final result.
The most important of these are the "battleground" or "swing" states with the largest number of electors, like Florida (29), Pennsylvania (20) and Ohio (18).
Elsewhere on the ballot
From 3 November onwards, Americans have started voting for every one of the 435 members of the House of Representatives (who serve two-year terms) and for 34 of the 100 senators (who serve for six years). They also will be choosing governors in 12 states, and will be casting votes in a multitude of referenda and local elections.
Congress does a final count
Once the electoral ballot votes are received, they are counted in a joint session of Congress.
By law, this takes place on 6 January. On that day, senators assemble at 12:30 pm and walk together to the House chamber. They are led by two Senate pages carrying mahogany boxes that contain the electoral vote certificates sent by the states.
The House session is presided over by the current Vice-President. Occasionally it's an awkward situation, as when Vice-President Al Gore presided over the counting in the 2000 presidential election he lost to Republican George W Bush.
At the session, the votes are examined, tallied and handed to the Vice-President who announces the results.
What if it's a tie?
If no presidential candidate receives 270 or more electoral votes in the count, the 12th Amendment directs the House to decide the presidential election. Each state's House delegation has one vote, and must pick from the top three candidates who received the most electoral votes.
The Senate would use a similar process to pick the vice-president.
Is the system outdated?
Over the years, there have been calls to do away with or reform the complex Electoral College, especially after the 2000 election when Gore won the popular vote but lost to Bush, who had more electoral votes.
John Hudak, a fellow in governance studies at the Brookings Institution, says most people want the person who wins the popular vote to become the president. But reform wouldn't be easy because it would require an amendment to the Constitution that would have to be ratified by three-fourths of states.
Before 2000, the most recent time a candidate lost despite winning the popular vote was in 1888.
"2000 was a really incredible exception," Hudak says. "Generally the Electoral College reflects the popular will."
With inputs from AP and AFP