Officials in Maricopa County, which includes Phoenix and where many votes are still uncounted, released a new batch of results around 9 p.m. Eastern on Thursday, and they showed Mr. Trump narrowing the gap slightly.
Maricopa will post its next report on Friday at 11 a.m. Eastern. Officials there said they had 204,000 more early ballots to process, and a smaller number of provisional and other ballots.
Mr. Trump was ahead in Georgia by about 1,300 votes with more than 98 percent of the estimated vote counted. Mr. Biden has been closing the gap, and the uncounted ballots are mostly in Democratic areas. The race could end up close enough for a recount.
Elections officials in Georgia were counting votes into the early hours of Friday.
The state might have been called already if not for a burst pipe at a site in Fulton County where election officials were counting absentee ballots, which delayed the counting process in and around Atlanta.
Mr. Biden has a slim lead in Nevada, about 11,000 votes, and he expanded it slightly after more results were released on Thursday. The race is much closer than experts expected going in, and the state will accept mail ballots received through Nov. 10 as long as they were postmarked by Election Day.
The next batch of results is expected to be announced around noon Eastern on Friday.
Mr. Trump is narrowly ahead in North Carolina with 95 percent of estimated votes counted. But North Carolina will accept mail-in ballots that arrive through Nov. 12, and it’s possible that the race won’t be called until then.
As of 2 a.m. Eastern, Mr. Biden trailed Mr. Trump by about 18,000 votes in Pennsylvania, and he has been steadily making up ground thanks to newly counted votes in major metropolitan areas of the state — mostly in the Philadelphia area, but some in Pittsburgh too. The vote tally is being continually updated.
The Trump campaign is fiercely contesting Pennsylvania ballots in the courts.
Reporting was contributed by Nick Corasaniti, Reid J. Epstein, Trip Gabriel, Kathleen Gray, Jennifer Medina, Alicia Parlapiano and Stephanie Saul.