Many of the facts he cited, however, are inaccurate.
Here's a look at some of Spicer's claims.
Fact: Photos from the 2013 inauguration clearly show white ground coverings being laid on the National Mall ahead of President Barack Obama's second swearing-in. Reporters who covered the event also recall the white plastic flooring that was laid along the National Mall to protect the grass.
"(The National Park Service) used a similar grass protective layer in 2013," a former senior Interior Department official told CNN Saturday, asking that his name not be used.
Claim: "This was also the first time that fencing and magnetometers went as far back on the Mall, preventing hundreds of thousands of people from being able to access the Mall as quickly as they had in inaugurations past."
Fact: The Secret Service, the agency responsible for securing the event, acknowledged that the secure area for this year's inauguration was larger than in years past, but the extra measures included only fences and bag checks and not magnetometers.
"The security perimeter for this inauguration was extended due to lessons learned and world events," a Secret Service spokesperson said. "Security fencing was placed around the National Mall this inauguration. There were seven access points where bag checks only were conducted." The spokesperson added that magnetometers -- which includes hand wands -- also weren't used.
Claim: "No one had numbers, because the National Park Service, which controls the National Mall, does not put any out."
Fact: It's accurate the National Park Service doesn't provide an official crowd count for the inauguration.
Claim: "We know that from the platform where the President was sworn in to 4th Street, it holds about 250,000 people. From 4th Street to the media tent is about another 220,000. And from the media tent to the Washington Monument, another 250,000 people. All of this space was full when the President took the oath of office."
Fact: It's not clear where Spicer's numbers originated, and the White House didn't respond when asked for more details. But the claim those areas were full when Trump took his oath of office is plainly untrue. Photos taken at noon on Friday show wide swaths of white flooring where people were not standing.
Claim: "We know that 420,000 people used the D.C. Metro public transit yesterday, which actually compares to 317,000 that used it for President Obama's last inaugural."
Fact: Spicer is using a range of numbers that don't make for a precise comparison. It's not clear where the 420,000 figure comes from -- in fact, the Washington Metro Area Transit Authority said the total ridership on Friday was higher: 570,557. But the 317,000 Spicer cited from 2013 was only until 11 a.m., not the entire day. Total ridership on the day Obama was sworn in four years ago stood at 782,000.
Trump at the CIA
Claim: "The President was also at the -- as you know, the President was also at the Central Intelligence Agency and greeted by a raucous overflow crowd of some 400-plus CIA employees. There were more than 1,000 requests to attend, prompting the President to note that he'll have to come back to greet the rest. They gave him a five-minute standing ovation at the end in a display of their patriotism and their enthusiasm for his presidency."
Fact: Trump was greeted by enthusiastic CIA employees at the CIA on Saturday, many of whom cheered loudly for the new President when he departed the room. Reporters in the room said there were roughly 400 people in attendance.
The length of his standing ovation, however, isn't precisely known.
The camera feed of the room was cut shortly after Trump finished to protect the identity of some of the national security officials in the crowd. While audio of the feed persisted for a minute or so later, music played over the sound and it wasn't clear how long the applause lasted. Reporters were also moved from the room as the ovation was ongoing. Trump departed the CIA about six minutes after he finished speaking.