The Republican Party has taken control of the Senate by picking up at least six seats from the Democrats
They have also strengthened their grip on the House of Representatives
Ballot initiatives expanding marijuana use and increasing minimum wage passed in some states
The economy, government dysfunction and President Obama's unpopularity were key issues
Anthony Zurcher
BBC News
Beauprez? Recchia? Djou? With elections taking place all over the US, the list of candidates is a grab-bag of interesting and sometimes tongue-twisting surnames.
NPR has posted a cheat sheet, external on how to pronounce some of the more challenging names on today's ballot.
Tara McKelvey
BBC News, Kansas
Corry Bliss, working out of this office in Topeka, Kansas, is the campaign manager for Sen Pat Roberts, a Republican. Mr Bliss is wearing a black jumper and is chewing gum - and walks stiffly across the parking lot. He says he's optimistic - "we're very encouraged" - but looks tense.
Image source, APSarah Palin has written, external about an old Ronald Reagan speech in support of Barry Goldwater's presidential campaign 50 years ago. She says the speech contains warnings about the "dangers of big government" and "affirms our call to action for today's election".
tweets:, external Turning out to vote is rather pleasant at polling station under the Hollywood sign. @BBCNewsUS #midterms2014 pic.twitter.com/Bbm1k5SSPW, external
Conservative American blogger Erick Erickson argues on the Politico website, external that even if the Republican Party ends up winning a majority in both the House of Representatives and the Senate, it will not initiate a programme of reform acceptable to grassroots conservatives.
"So we might well see a Republican Congress in name after Election Day," he says, "but its small-government rhetoric is certainly not going to fool or win over the party base."
For those planning on staying up late to watch the results unfold, the LA Times' man in Washington has a warning - David Lauter, external says it could be days, possibly even weeks, until a full tally of votes is complete. Read what he has to say here, external.
tweets:, external POLITICO's @DavidNather tells me Republicans likely to pick more fights with Obama if they take Senate. Gridlock here to stay.
In a world where it seems almost obligatory for an electioneering politician to be photographed smiling with a youngster, Republican Thom Tillis is no exception. Here he is campaigning for a Senate seat in Charlotte, North Carolina.
Image source, Reuterstweets:, external Louisville, Kentucky - busiest congressional poll the local election official has ever seen @BBCNewsUS pic.twitter.com/CmVUu6RUTg, external
Our BBC correspondents have pulled together a few reasons why Democratic Party candidates might face problems due to their association with President Barack Obama.
• An ABC News/Washington Post poll suggested 44% of people see President Obama favourably, down from 49% in January and 60% as his second term began
• The survey also indicated that half of adults and 53% of likely voters view him unfavourably
• This is close to an all-time personal low, according to Real Clear Politics
• Bill Clinton, Ronald Reagan and Dwight Eisenhower all had higher approval ratings at this stage of their presidencies, according to Gallup, but George W Bush's figures were slightly lower.
tweets:, external "I don't anticipate you'll hear from him tonight" @PressSec says of POTUS, says he will watch results in the residence.
Former presidential candidate Mike Huckabee uses a blog post, external to tell American voters "what today is all about", reassuring them that Republicans do not want to "take away your birth control pills or bring back slavery".
The bass guitar-playing Fox News host adds: "So if you like the direction America's been heading, vote for Democrats, and keep speeding that way for two more years. If you think we desperately need to step on the brakes before we reach the cliff, then vote Republican.
Image source, APtweets:, external In Osceola, voters are poised to oust Democrats due to dissatisfaction with the economy bbc.in/1up0XTV
Many American voters have said they are tired of the mid-term election campaigns. But there is a chance that there are more to come.
Both Louisiana and Georgia are tipped as states where it is likely that no candidate will win more than 50% of the vote outright.
In such a scenario, Louisiana would have to hold a run-off election in December, and Georgia would not hold its run-off until January 2015 - which could potentially mean a long wait to determine who holds power in the Senate.
A campaigner in San Francisco makes the most of the mid-term elections by canvassing to save a local park
Image source, ReutersA rally was held on Monday night at a church in St Louis, Missouri, urging people to vote in the mid-terms
Image source, Getty Imagestweets:, external Thanks to all our dedicated #Arizona poll workers! pic.twitter.com/xRzqhVONdY, external
Jon Sopel
North America editor
It's always interesting at election time in politics to ask the question - are people voting for the person they want the most, or the candidate they mind the least?
If it is the former, it is normally a good guide that turnout will be high - think Narendra Modi earlier this year in India or Obama in 2008, or Tony Blair in Britain in 1997. Those were "time for change" elections.
In the United States at the moment the mood is sullen, which occasionally tips into anger. It is a plague-on-both-your-parties election.
Image source, Getty ImagesBrendan Buck, VP of Communications at AHIP
@BrendanBuck tweets:, external Come on folks, need to step up our game on useless anecdotes about turnout levels in various precincts and what it means.
What goes on inside the mind of a vote-hungry US senator? This BBC report looks at the strategies senators are likely to consider to try to stay in power.
You can check out more BBC videos in the "key video" section of this page.