10 swing states that will determine US election

One of the most divisive US presidential elections in history is nearly over. By the end of election day today more than 130m Americans out of an eligible population of 225m are expected to have cast ballots across 50 states.

But just winning the popular vote will not necessarily send Hillary Clinton or Donald Trump to the White House. Instead, the US’s complicated system makes the night a race to secure a majority of the 538 votes in the electoral college – 270 or more.

What should you be watching for and when is the drama likely to unfold?

The swing states to watch
The  election is being fought hardest in 10 states: Arizona (11 electoral college votes), Colorado (9), Florida (29), Iowa (6), Nevada (6), New Hampshire (4), North Carolina (15), Ohio (18), Pennsylvania (20) and Virginia (13).

Mrs Clinton starts with an advantage in the electoral college and can afford to lose traditional battlegrounds such as Florida and Ohio. But if that happens, falling short in states such as Pennsylvania and North Carolina could prove fatal to her ambitions. If Mr Trump does not win in Florida and Ohio, his chances of victory will be slim. One key could be the size of the turnout of Latino voters in Arizona, Florida and Nevada, which have large Hispanic populations. Another could be whether African-American voters go to the polls at a high rate in North Carolina and Ohio.

Georgia (16), Michigan (16), Utah (6) and Wisconsin (10) could all emerge as important, especially in a tight race. Georgia and Utah are traditionally Republican strongholds, while Michigan and Wisconsin are part of a “Blue Wall” the Democrats had hoped would help guarantee a Clinton victory.

What happens when and how late will I need to stay up?
6pm EST (11pm GMT): the first polls close in Indiana (11), home to Trump running mate Mike Pence, the state’s governor, and Kentucky (8).

Both states are heavily Republican and likely to be carried by Mr Trump.   7pm EST (midnight GMT): polls close in battleground states Florida (29) and Virginia (13), and Georgia (16), South Carolina (9) and Vermont (3).

The counting of ballots across the nation will go on well into tomorrow. You can, however, expect the US media to begin calling the races in safe Democratic and Republican states such as Kentucky, Vermont and South Carolina, but do not expect early calls in Florida or Virginia. In 2012, a winner was not declared in Florida until days after the election. A result in Virginia was not declared until after midnight.   7.30pm EST (12.30am tomorrow GMT): polls close in two more important states: Ohio (18) and North Carolina (15). They also shut in West Virginia (5), where Mr Trump is heavily favoured.

Mr Trump has done a lot of campaigning in Ohio, hoping to capitalise on the appeal of his protectionist trade policies in the rust belt state. In 2012, Mitt Romney had been declared the winner in four of the five states called before 8pm. President Barack Obama had won only Vermont.  8pm EST (1am GMT): things start to heat up. Polls close in the crucial state of Pennsylvania (20) and in Alabama (9), Connecticut (7), Delaware (3), the District of Columbia (3), Illinois (20), Michigan (16), Kansas (6), Maine (4), Maryland (10), Massachusetts (11), Mississippi (6), Missouri (10), New Jersey (14), Oklahoma (7), Rhode Island (4) and Tennessee (11).

Expect a flurry of declarations in safe Republican and Democratic states. If Mrs Clinton does not take Pennsylvania it will be a big blow, especially because she chose to spend the last night of her campaign in Philadelphia alongside her husband and the Obamas.

In 2012, it took almost two hours for Mr Obama to be named the winner in the state. It was the first real battleground to be called.  9pm EST (2am GMT): polls close in Colorado (9), Wisconsin (10) and Texas (38). They also shut in Louisiana (8), Minnesota (10), Nebraska (5), New Mexico (5), New York (29), South Dakota (3) and Wyoming (10). Look for early calls for Mrs Clinton in the population-heavy states of New York and New Jersey where she is firmly favoured.   10pm EST (3am GMT): polls are closing in western states Arizona (11), Idaho (4), Montana (3), Nevada (6) and Utah (6) as well as the mid-western farm state of Iowa (6).

In 2012, this was when Mr Obama began really piling up the victories. Although it has a long tradition of voting Republican in presidential races, Arizona has been seen as more of a battleground this year. Utah is also interesting this year as conservative Mormon Evan McMullin has polled well in the state and could even win it.   11pm EST (4am GMT): the polls close in the biggest electoral prize on the map – solidly Democratic California (55) – as well as Washington state (12), Oregon (7) and North Dakota (3).  Midnight EST (5am GMT): polls close in Alaska (3) and Hawaii (4). Time for concession speeches? In 2008 and 2012, John McCain and Mitt Romney each gave nationally televised concession speeches shortly after midnight eastern time. If neither candidate gets to 270 by the end of the process, the Republican-controlled House of Representatives will decide who the next president should be.

What are the main factors to watch?
With polls showing voters having negative opinions of both main candidates, one of the key factors on election day could be the enthusiasm of their bases. If black, female, Latino and young voters do not turn out in significant numbers, it could represent a blow to Mrs Clinton. Likewise if white, working-class voters do not go to the polls in large numbers it would hurt Mr Trump.

Turnout among African-American voters looks likely to be lower than it was in 2008 and 2012. But Mr Trump’s provocative immigration policies mean a growing Hispanic electorate is expected to vote heavily against him.

Which are the important groups of voters to track?
Polls show the biggest divide among voters this year could be based on education. Mr Trump’s strongest support has been with older, high-school educated white voters. But Mrs Clinton is expected to become the first Democratic presidential candidate to win among college-educated white voters since pollsters began gathering the data in 1952.

Is today the only day Americans can vote?
No, 37 states allowed early voting and in many parts of the country people queued for hours. About a quarter of the expected electorate voted by Saturday.

What other races should I keep an eye on?
Americans will also be voting for 34 of the US Senate’s 100 seats and for all 435 seats in the House of Representatives. Twelve governorships are up for grabs.

The big question beyond the presidency is what will happen in the Republican-controlled Congress. A good night for Democrats would see them win five seats and regain control of the Senate (four if Mrs Clinton wins as that would mean vice-president Tim Kaine would cast the deciding vote), while also whittling down the Republicans’ 30-seat majority in the 435-seat House. It is extremely unlikely Democrats will regain control of the House.