Republican Donald Trump won the key battleground state of Ohio on Tuesday and led Democrat Hillary Clinton in a series of other states that were too close to call, including Florida and North Carolina, in a surprisingly close race for the White House.
The U.S. dollar sank and stock markets slammed into reverse in wild Asian trade on Wednesday as early results pointed to a nail-biter and investors stampeded to safe-haven assets.
Sovereign bonds and gold shot higher while the Mexican peso went into near free-fall as investors faced the possibility of a Trump win. Investors worry a victory by the New York businessman could cause economic and global uncertainty.
With voting completed in 44 of the 50 U.S. states, the race was tight in Florida, North Carolina, Pennsylvania and New Hampshire, leaving the race for the White House on a knife's edge.
Trump's win in Ohio, with 18 electoral votes, and his edge in Florida and North Carolina gave him an early advantage in the state-by-state fight for 270 Electoral College votes needed to win.
Clinton had more options to reach 270, with Trump needing a virtual sweep of about six toss-up states to win. But a Trump win in all those three states would leave Clinton needing to win the remaining battlegrounds including Pennsylvania, Michigan and either Nevada or New Hampshire.
Both candidates scored victories in states where they were expected to win. Trump captured conservative states in the South and Midwest, while Clinton swept several states on the East Coast and Illinois in the Midwest.
After running close throughout the night in Virginia, Clinton pulled out the swing state that is home to her running mate, Senator Tim Kaine.
At 8:55 p.m. EST (0155 GMT on Wednesday), Clinton acknowledged a battle that was unexpectedly tight given her edge in opinion polls going into Election Day.
She tweeted: "This team has so much to be proud of. Whatever happens tonight, thank you for everything."
With 95 percent of the vote counted in Florida, Trump led Clinton by about 130,000 votes out of 9 million cast. In North Carolina, Trump led by about 100,00 votes out of 3.9 million cast.
As of 10:35 p.m. EST (0335 GMT on Wednesday), Trump had 167 electoral votes to Clinton's 131, with U.S. television networks projecting the winner in 31 of the 50 states and the District of Columbia.
Before Tuesday's election, Clinton led Trump, 44 percent to 39 percent in the last Reuters/Ipsos national tracking poll. A Reuters/Ipsos States of the Nation poll gave her a 90 percent chance of defeating Trump and becoming the first woman elected U.S. president.
Also at stake on Tuesday was control of Congress. Television networks projected Republicans would retain control of the House of Representatives, where all 435 seats were up for grabs.
In the Senate, where Republicans were defending a slim four-seat majority, Democrats scored their first breakthrough in Illinois when Republican Senator Mark Kirk lost re-election. But Republicans Rob Portman in Ohio and Marco Rubio in Florida won high-profile Senate re-election fights.
In a presidential campaign that focused more on the character of the candidates than on policy, Clinton, 69, a former U.S. secretary of state, and Trump, 70, accused each other of being fundamentally unfit to lead the country.
Trump again raised the possibility on Tuesday of not accepting the election's outcome, saying he had seen reports of voting irregularities. He gave few details and Reuters could not immediately verify the existence of such problems.