Joe Biden, the Democratic candidate for the U.S. president, is projected to win Arizona, with its 11 electoral votes, Fox News and the Associated Press reported.
Biden leads Trump with 51 per cent of the vote and more than 2.5 million ballots cast.
Arizona has historically been a Republican stronghold, but Biden’s bid to flip the state was boosted by a growing voter-age Latino population and residents moving from California to Arizona.
Arizona is the only state to flip from Republican to Democrat support so far.
Biden has a narrow electoral lead with 238 votes compared to 213 for Trump, both candidates need 270 votes to win.
The election is now pinned on a handful swing states that have yet to declare a winner, Georgia, Michigan, North Carolina, Wisconsin and Pennsylvania.