But as the first polls began to close, there were no reports of the unrest many had feared, with voters encountering only minor hiccups as they had their say on the country’s future.
The most significant development of a fraught election day came when a US federal judge ordered the US Postal Service to conduct a “sweep” of processing facilities in swing states in order to search for misplaced ballots.
The postal service, which has been subject to sharp cutbacks under the Trump administration, said that approximately 300,000 ballots received entry scans but not exit scans, meaning that there was no record they had been sent out for delivery.
The order by Emmet Sullivan, a district judge in the District of Columbia, spans numerous postal districts across 15 states.
Elsewhere, fears that the electoral process would be undermined by unrest and voter suppression proved largely unfounded.
In Pennsylvania, one of the most closely contested states, around 1,000 National Guard troops who had mobilised around Philadelphia’s City Hall fell back, but remained on alert.
The feared army of so-called poll watchers summoned by Mr Trump appeared to have drawn its ranks from deserters, with only sporadic reports of individuals attempting to oversee counts.
Those questioning the legitimacy of the voting process largely did so on social media. They included Mr Trump’s election day operations director, Mike Roman, who claimed “bad things” were happening in Philadelphia. The city’s district attorney office declared his remarks “deliberately deceptive.”
Instead, the increasingly familiar electoral scourge of technology reared its head in other ways.
Voters in swing states including Pennsylvania, Florida and Michigan were on the sharp end of a flurry of robocalls - automated spam phonecalls - imploring them to stay home or cast their vote on Wednesday. According to the US Department of Homeland Security, the FBI is looking into the apparent disinformation campaign.
Elsewhere, technical glitches caused temporary blackouts at a few polling stations. Other problems were a sign of the times. In one voting precinct in Des Moines, Illinois, excess hand sanitiser on voters’ hands caused a ballot scanner to temporarily malfunction.