Democratic Senator Barack Obama has been elected the first black president of the United States, according to projected results.
He is projected to have won enough states to guarantee that he has beaten Republican rival John McCain.
He has so far held most of the states that voted Democrat in 2004, as well as seizing at least four from the Republicans.
Several other key swing states are hanging in the balance.
In Indiana and North Carolina, with most of the vote counted, there was less than 0.5% between the two candidates.
However, the popular vote remains close. At 0345 GMT it stood at 50.7% for the Democratic Senator from Illinois, against 48.2% for Arizona Senator McCain.
Mr Obama captured the key battleground states of Pennsylvania and Ohio, before passing the essential figure of 270 electoral college votes at 0400 GMT, when projections showed he had also taken California and a slew of other states.
The main developments include:
Faton Fall, 40, a black voter queuing at a Baptist church in Chicago, said: "It means a lot to me. I'm overwhelmed. I can't say more."
There are also elections to renew the entire US House of Representatives and a third of US Senate seats.
Democrats are expected to expand majorities in both chambers.
They need to gain nine Senate seats to reach a 60-seat majority that would give them extra legislative power.
In the presidential vote, under the US Electoral College system, states are allocated votes based on their representation in Congress.
In almost every state, the winner gets all these college votes.
To become president, a candidate needs to win a majority across the country - 270 college votes out of a possible 538.
The presidential election has been the most expensive in US history - costing $2.4bn, according to the non-partisan Center for Responsive Politics.