Winners and losers: The outcome of Pennsylvania's Senate race had never been much in doubt but for many Democrats, the defeat of Rick Santorum, the third most senior Republican in the Senate, was the sweetest moment of the night. A devout Catholic who opposes abortion and embryonic stem cell research and regards contraception as wrong, Mr Santorum has compared homosexuality to incest and adultery.
A supporter of the war in Iraq, Mr Santorum was one of only a handful of Republican candidates in close races who refused to distance himself from President George Bush during the campaign.
He was the most prominent casualty on a night that saw at least five Republican senators lose office, including Rhode Island's Lincoln Chafee, the most moderate Republican in the Senate and the only senator in his party to vote against the Iraq war.
Perhaps the happiest senator this week is Joe Lieberman, the former Democratic vice-presidential candidate who lost the Democratic nomination to businessman Ned Lamont. Mr Lieberman, a national security hawk who has been more loyal to Mr Bush on Iraq than many Republicans, won his Connecticut seat as an independent, despite a well-funded Democratic campaign against him.
He will be joined as an independent by Vermont's Bernie Sanders, who will become the first self-proclaimed socialist to sit in the US Senate.
It was a night of firsts for the Democrats, with Nancy Pelosi set to become the first woman Speaker of the House of Representatives, next in line to the president after vice-president Dick Cheney. Keith Ellison of Minnesota is set to become the first Muslim member of Congress.
Perhaps the only big Republican winner of the night was California governor Arnold Schwarzenegger, who bounced back to victory after polls last year predicted defeat.
Chuck Schumer and Rahm Emmanuel, who ran the Democratic Senate and House campaigns, had a more successful night than most pundits predicted. They will have to share some of the glory with Democratic National Committee chairman Howard Dean, whose strategy of putting party operatives in all 50 states may have helped to win unexpected seats in the west of the country.
Hillary Rodham Clinton's landslide Senate victory in New York, where she won 67 per cent of the vote, confirms her status as the front runner for the Democratic presidential nomination in 2008.
The biggest losers were not on Capitol Hill at all but in the White House and the Pentagon - the president, his political adviser Karl Rove and defence secretary Donald Rumsfeld.
Mr Rumsfeld, the appointed scapegoat for the debacle in Iraq, was clearing out his office yesterday, less than a week after Mr Bush said he would still be defence secretary in 2009. Mr Rove woke up yesterday to find his dream of a permanent Republican majority in shreds and his strategy of polarising voters and focusing on the conservative base widely blamed for his party's defeat.
Mr Bush is the biggest loser of all, doomed to spend the last two years of his presidency at the mercy of a Democratic-controlled Congress, watching his staff called one by one to testify about what went wrong in Iraq and knowing that the American public has just issued a resounding rejection of both this president and his policies.