Media playback is unsupported on your device Media caption Hang on, what ARE the US 'mid-terms'?

Millions in the US and across the world are following the election results as they come in. There are hundreds of races - which ones are worth keeping an eye on?

Americans have been filling polling stations on Tuesday to elect 35 senators and all 435 members of the House of Representatives, as well as 36 state governors and countless state officials.

Polls in many areas have closed.

It is a crucial election for President Donald Trump, as his Republican Party currently controls both houses of Congress.

Here are some of the key races to watch - and what's happened so far.

The early results

A huge setback for Democrats as they lose their Senate seat in Indiana. That makes their path to seizing control of the upper chamber very narrow indeed. It's a state that Trump won easily in 2016.

A key Kentucky district seen as a bellwether has been held by Republicans but there was some good news for Democrats in Virginia.

Virginia congresswoman Barbara Comstock has lost her seat in the House to Democratic challenger Jennifer Wexton, and she's being seen by the BBC's Anthony Zurcher as the first possible casualty of a Democratic "blue wave".

Democratic incumbent senators in the eastern part of the country have retained their seats, including Massachusetts' Elizabeth Warren and Virginia's Tim Kaine. No surprises there.

Independent Bernie Sanders has glided to an easy win in Vermont, securing a third term in the senate.

What happened at 19:00 EST (00:00 GMT)

Most polls closed in two of the most closely-watched governors' races, Florida and Georgia.

In Florida, the Democratic Mayor of Tallahassee, Andrew Gillum, a left-wing progressive who wants to become the state's first black leader, faces Republican Ron DeSantis, a Trumpist conservative.

Image copyright Getty Images Image caption Ron DeSantis (left) and Andrew Gillum are fighting to become Florida's governor

The fight for a Senate seat has put incumbent Bill Nelson, a Democrat who has served since 2000, against outgoing Republican Governor Rick Scott, in what is one of the most expensive races in the country.

President Trump loves Florida. A double Republican win here would give the White House a huge morale boost.

In neighbouring Georgia, Democrat Stacey Abrams hopes to become the country's first black female governor in one of the most contentious races in this year's mid-term election. She faces Republican Brian Kemp, Georgia's current secretary of state, the top official overseeing the election.

Image copyright Reuters Image caption The race between Stacey Abrams (D) and Brian Kemp (R) is one of the most fiercely contested

The campaign, which has drawn national attention, has been embroiled in claims of voter suppression, and may not even be over on Tuesday: if neither candidate gets a majority of the vote, the decision will go to a run-off election on 4 December.

In a House race of note, Republican Rep Karen Handel, elected in a closely-fought special election in 2017, faces gun control activist Lucy McBath, whose son was killed in a dispute about loud music, in the suburban Atlanta 6th district.

Polls also close in South Carolina, Vermont and Virginia, where Republican Rep Dave Brat is fighting for re-election in the Richmond-area (7th district) against Democrat Abigail Spanberger, a former CIA officer. Mr Brat won his seat after famously defeating House Majority Leader Eric Cantor in 2014 in a Republican primary.

A Brat defeat - if it comes on the heels of Democratic victories elsewhere - would be interpreted as a good sign for those cheering the Democratic cause.

At 19:30, polls close in North Carolina, Ohio and West Virginia.

What happened at 20:00 EST (01:00 GMT)

This was an action-packed hour that could decide who will control the Senate. But you'll need to pay close attention to know what's happening - there's a lot going on.

Polls closed in New Jersey, where the race for the 7th district is playing out between Rep Leonard Lance, who has represented the area since 2008, and Democrat Tom Malinowski. Democrats are hoping to make some gains in an area that is critical of President Trump.

Democrats also have high hopes in Pennsylvania, and one race worth watching is the 1st district.

Republican Rep Brian Fitzpatrick, a moderate former FBI agent, faces Democrat Scott Wallace, who has spent huge sums of his own wealth to fund his campaign - his family's philanthropic foundation, the Wallace Global Fund, is reportedly worth more than $140m (£107m).

Media playback is unsupported on your device Media caption What do American voters care about?

Polls also closed in Alabama, Connecticut, Delaware, District of Columbia, Illinois, Maine, Maryland, Mississippi, Oklahoma, Rhode Island and Tennessee.

In Missouri, two-term Democratic Sen Claire McCaskill hopes to keep her seat against Republican Josh Hawley.

First polls closed in Kansas, Massachusetts, Michigan, where Democrat Rashida Tlaib hopes to become the first Muslim woman in Congress, New Hampshire and South Dakota.

At 20:30, polls closed in Arkansas.

What happened at 21:00 EST (02:00 GMT)

Polls closed in Texas. One to watch is the 7th district of west Houston suburbs, a former GOP stronghold that narrowly chose Hillary Clinton over Donald Trump. Republican Rep John Culberson faces Democrat Lizzie Fletcher.

The race for the Senate in this traditional red state is between incumbent Ted Cruz, a former Republican presidential candidate, and Democrat Beto O'Rourke, a rising star who wants to become the party's first senator for Texas in three decades.

He's been getting a lot of attention and raising loads of money, but a win for Mr O'Rourke looks unlikely. It would suggest there's been a big swing to the Democrats nationwide if he gets over the line.

Media playback is unsupported on your device Media caption Apathy isn't the only reason why so many Americans don't vote

Polls close in Colorado, Louisiana, Nebraska, New Mexico, New York, Wisconsin and Wyoming.

In Minnesota, Republican Rep Erik Paulsen faces a big challenge from Democrat Dean Phillips in the Twin Cities suburbs (3rd district). Mrs Clinton won in the area by nine points.

You're doing well if you're still keeping up. You might have the state of play now in the Senate and the House, but don't bet on it.

What happened at 22:00 EST (03:00 GMT)

Polls closed in Iowa, and a key race to watch is in Des Moines (3rd district), one of the areas that swung for Barack Obama in 2012 but backed Mr Trump two years ago. Republican Rep David Young faces Democrat Cindy Axne, a small business owner.

In Nevada, Republican Sen Dean Heller faces Democrat Rep Jacky Rosen, and Democrats are optimistic about winning this seat.

Polls also closed in Montana, and Utah. First polls close in Idaho and North Dakota.

Jon Tester's attempt to keep his Senate seat in Montana has irked the president personally - Mr Trump said he has never forgiven the Democratic senator for raising questions about his personal doctor, Ronny Jackson, when he was in the frame to be secretary of veterans' affairs.

23:00 EST (04:00 GMT)

We've hit the west coast. If you don't know which party has had a good night so far, you've probably been napping.

Polls close in California, and it will be interesting to see how traditionally Republican areas will vote. One of the key races is taking place in the 45th district, in Orange County. Mitt Romney won there in 2012 but Mrs Clinton was favoured here in the last election. Republican Rep Mimi Walters faces Democrat Katie Porter, a law professor.

Polls also close in Oregon and Washington.

00:00 EST (05:00 GMT)

Polls close in Hawaii. Polls close in Alaska between now and 01:00 (06:00 GMT).

Some nail-biter races could still be in the balance - but there should be champagne corks popping somewhere by this stage.