Polling stations closed in more than half of the 50 US states on Tuesday, in a landmark contest that saw tens of millions of Americans cast their ballots amid the coronavirus pandemic.
Voters, many wearing masks and maintaining social-distancing to guard against the spread of the new coronavirus, experienced long lines in some locales.
Preliminary results showed that Trump won the states of Indiana, West Virginia, Kentucky, Oklahoma, Tennessee, Alabama, North Dakota, South Dakota and Wyoming.
This is while Biden emerged winner in Virginia, Vermont, District of Columbia, Maryland, Massachusetts, Delaware, New Jersey, Connecticut, Illinois, Rhode Island.
Trump and Biden are running neck-and-neck in the vital battleground of Florida and have a tight race in North Carolina, Georgia, and Texas.
Biden put Trump's handling of the pandemic at the center of his campaign and has held a consistent lead in national opinion polls over the Republican president.
According to an Edison Research exit poll on Tuesday, a third of American voters listed the economy as the issue that mattered most to them when deciding their choice for president, while two out of 10 cited the coronavirus.
In the national exit poll, four out of 10 voters said they thought the effort to contain the virus was going "very badly."
Final results may take days to be announced as counting mail-in ballots is expected to be a time-taking process.