Trump and Biden launched personal attacks as they dealt with issues such as coronavirus response, racial justice, the economy and each other's fitness.
Biden asked Trump to shut up after being interrupted while answering a question about whether he supported ending the Senate filibuster or adding more justices to the Supreme Court.
On Tuesday, Twitter used began trending #DebateTuesday, #Debates2020 and #PresidentialDebate2020 and the micro-blogging site was flooded with memes on Trump and Biden.
The mail-in ballots were marked for President Trump and were found discarded in a dumpster near the elections building in Luzerne County, Pennsylvania.