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
... for those of you who've just joined us. Millions in the US are voting in mid-term elections which will decide who controls the Senate and pave the way for the 2016 race for the White House. For detailed features, videos and analysis, check out the BBC's special report on the mid-terms.
tweets:, external If the pundits are right that people care so much about the deficit, Dems are gonna sweep the House and Senate today.
Nick Bryant
BBC News, Kentucky
They love a close race in Kentucky, and the Democratic challenger Alison Lundergan Grimes reckons this Senate election will end in a photo-finish. But the smart money is on Mitch McConnell to beat his 35-year-old opponent, who was just five when he first won election to the Senate. Grimes, Kentucky's secretary of state, thought that distancing herself from Barack Obama would be a brilliant strategy. But it boomeranged because she wouldn't even say whether she voted for the president in 2008 and 2012. It not only made her sound silly, but cowardly.
Image source, Getty ImagesFor a flavour of electioneering US-style, the Politico website has compiled a montage, external of what it says are the most watched campaign ads on Facebook and YouTube.
Tara McKelvey
BBC News, Kansas
Polls have opened in Leawood, Kansas, the site of a closely watched Senate race. If Pat Roberts, the incumbent, loses, it could cost Republicans their chance of a majority in the Senate.
post a video: Why I'm Not Voting in the Midterms, external
CNN reports that the 2014 mid-terms, external are a great election year for what it calls the "bad boys" of Congress. It quotes US political analyst David Wasserman as saying "we've rarely seen this many members who are in trouble personally or legally with strong chances of winning".
The White House has just announced that Mr Obama will be in Myanmar on 14 November to meet opposition leader Aung San Suu Kyi, AFP reports. Ms Suu Kyi, who spent most of the past two decades in some form of detention because of her efforts to bring democracy to military-ruled Myanmar, has become an international symbol of peaceful resistance in the face of oppression.
Image source, EPAThe Democratic Congressional Campaign Committee issued a statement, external on Monday, saying: "House Democrats have succeeded on every measure within our control and have kept every Democratic incumbent in a competitive position to win."
The Washington Post, external argues that Democrats have given up hope of winning back the House, and already skipped ahead to winning the post-election blame game.
The mid-term elections are projected to cost nearly $4bn (£2.5bn), according to the Center for Responsive Politics. This would make it the most expensive mid-term election in US history. The BBC examines where the money comes from and what it is paying for.
Image source, Reuterstweets:, external Here's my piece on whether black voters offer any hope for Grimes, external. Also, Mitch reaching out to black voters lately.
tweets:, external Happy Election Day! Here's the view from social media, external
tweets:, external "I'm just seriously concerned about the state of things in America today," a woman voting for McConnell told me. #kysen
Voters begin to cast their ballots in Arlington, Virginia.
Image source, EPAtweets:, external Great way to start out Election Day. At the CNN Magic Wall with @JohnKingCNN and @jmartnyt. See photo, external
One reason many analysts predict a Republican victory is because President Obama's popularity rate has failed to climb much above 40%, despite recent improvements in the economy. And, as this graphic shows, a large proportion of voters see their Congress vote as a vote against Mr Obama.
Kim Ghattas
BBC News, Arlington, Virginia
Virginia is one of the many states where the incumbent senator has a comfortable lead, so there is less voter enthusiasm. But in North Carolina or Louisiana, Georgia, even Iowa, where a Democrat has held the seat for three decades, the race is highly competitive.
Tuesday's focus is on the Senate, where Republicans are hoping to seize a majority. But we shouldn't forget there's a battle for the lower chamber too, the House of Representatives, where the Republicans have a lead of 233 to 199.
They are expected to maintain or increase that lead - some Republicans have even been talking about finishing the night with a record number of seats in the House, as this Guardian report, external outlines.
@beth0505 in Michigan tweets, external: Back from voting! There was good turn out for 7:00 am! I was 16 in there was line at door n waiting to vote when we left! #Vote2014
Despite many analysts predicting a Republican victory, US Vice President Joe Biden says he is optimistic.
"I don't agree with the oddsmakers," Mr Biden told CNN, external. "I predict we're gonna ... keep the Senate."
Image source, AP