He won Florida, Ohio, Iowa and North Carolina, while Democrat Mrs Clinton took Virginia and Nevada, ABC projects. Pennsylvania is too close to call.
New Hampshire, Michigan and Wisconsin – which were meant to be part of the Clinton firewall – are deadlocked, too.
Mr Trump’s Ohio win was a big boost to him, as no Republican has ever taken the White House without winning the Midwestern bellwether.
Iowa last voted for a Republican in 2004.
