What’s the truth about online viewership of Trump’s inauguration? We may never know.

Fact or “alternative fact?” We may never know.

White House spokesman Sean Spicer on Monday stuck by his claim that more people watched the inauguration of Donald Trump last Friday than any other in history.

“It was the most watched inaugural,” Spicer said, repeating an assertion he’d made over the weekend, when both he and President Trump complained that the news media was intentionally downplaying the size of the crowd. Trump told an audience at the headquarters of the Central Intelligence Agency that “a million, a million and a half” people packed the National Mall from the Capitol to the Washington Monument, nearly two miles away.

Those assertions were contradicted both by photos and by subway ridership numbers that suggested Trump’s inauguration was less well attended than either of Barack Obama’s or George W. Bush’s second one. The New York Times on Sunday quoted two crowd counting experts who estimated the crowd on the National Mall at 160,000 people.

On Monday, Spicer offered a new measurement of those who saw the inauguration, combining a figure of 31 million television viewers from the Nielsen company, which provides TV ratings, with 16.9 million more that he said had clicked on a CNN live stream of the event. That total would surpass the 41 million viewers that Nielsen said watched Ronald Reagan’s 1981 inauguration.

“If you add up the network streaming numbers, Facebook, YouTube, all of the various live streaming that we have information on so far, I don’t think there’s any question it was – that it was the largest watched inauguration, ever,” Spicer said.

But there is almost no way to verify Spicer’s assertion about total viewership, and some reason to doubt it.

CNN spokesman Matt Dornic agreed in an email that some 16.9 million people using smart phones, tablets or computers had licked on the live CNN feed of inauguration coverage between 6 a.m. to midnight on Friday.

But only 2.3 million were viewing the live stream simultaneously at 12:15 p.m. Friday, the hour when Trump was being sworn in, Dornic said. Before and after the inauguration, the simultaneous viewership averaged between one and 1.5 million, Dornic said.

Dornic said he didn’t immediately have data on how long the average person continued viewing once they clicked on the video feed.

Millions of others might have viewed the inauguration elsewhere. McClatchy, the Washington Post and the New York Times, for example, also offered live streams on their websites. So did BBC and Facebook and YouTube and uncounted other television outlets.

A Facebook spokesman, Andy Stone, said 1.3 million people viewed video or live stream on the Facebook Page of the Joint Congressional Committee on Inaugural Ceremonies. Some of them viewed it once the actual event was over.

An analyst at the Nielsen Company, a firm that measures retail and media consumer habits, said it attempts to measure audiences of live streams and video on digital platforms but wasn’t ready to offer numbers on the inauguration.

“It’s hard to prove and it’s hard to disprove,” said the analyst, who asked not to be identified because he wasn’t authorized to speak publicly.

He noted little benefit to the company in offering a candid assessment.

“We’re trying not to draw his wrath,” the analyst said, referring to Trump.

Tim Johnson: 202-383-6028, @timjohnson4