WASHINGTON — President Trump took aim at reporters on Thursday for more than an hour at an impromptu White House news conference.

“The press has become so dishonest,” he said, and not talking about it would be “doing a tremendous disservice to the American people.” He added that the “level of dishonesty is out of control.”

In accusing the news media, though, Mr. Trump uttered several falsehoods of his own. Here is a list of some of the most important.

‘It was the biggest Electoral College win since Ronald Reagan.’

Mr. Trump won 306 Electoral College votes (and ended up with 304 officially), well above the threshold needed to secure the presidency but well behind several of his most recent predecessors. President Barack Obama won 332 Electoral College votes in 2012 and 365 four years earlier. President Bill Clinton received 370 Electoral College votes in 1992 and 379 in 1996. And President George Bush won 426 Electoral College votes in 1988.

When a reporter pressed Mr. Trump on the claim, he laid the blame elsewhere. “I was given that information,” he said.

‘That circuit is in chaos and that circuit is frankly in turmoil.’

Mr. Trump said the United States Court of Appeals for the Ninth Circuit, which upheld a temporary restraining order on his targeted travel ban, was “in chaos.”

There is no evidence of that. The decision by the Ninth Circuit’s three-judge panel in the travel ban case was unanimous.

Mr. Trump also claimed that the court was “a circuit that has been overturned at a record number.” He was apparently referring to the Ninth Circuit’s reversal rate, which the president cited correctly: “I find that hard to believe, that is just a number I heard, that they are overturned 80 percent of the time.”

PolitiFact found that of the cases the Supreme Court took up from the Ninth Circuit, about 79 percent were reversed from 2010 to 2015.

But that was not the highest rate among the nation’s 13 appeals courts. The Sixth Circuit (87 percent) and 11th Circuit (85 percent) each had a greater percentage of reviewed decisions reversed. For all appellate court cases in that period, the Supreme Court reversed decisions about 70 percent of the time.

‘Our administration inherited many problems across government and across the economy. To be honest, I inherited a mess.’

By most definitions, the economy is not a mess, nor is it in recession. The unemployment rate in January was 4.8 percent, compared with 7.8 percent in January 2009, when Mr. Obama took office.

Last month, the economy added 227,000 jobs, even though the unemployment rate is already low. The number of people filing new claims for jobless benefits continues to hit lows not seen in decades.

Other measures suggest the same thing, as our colleagues at The Upshot report: The economy seems to be taking off.

‘But a new Rasmussen poll just came out just a very short while ago, and it has our approval rating at 55 percent and going up.’

Mr. Trump correctly cited the daily presidential tracking poll by Rasmussen. But the poll is an outlier, giving Mr. Trump an approval rating several points higher than others in the field. Real Clear Politics’ average of approval ratings finds that 44.6 percent of Americans approve of the job Mr. Trump is doing, compared with 50.3 percent who disapprove.

Gallup’s daily job approval tracker puts Mr. Trump’s approval rating at 40 percent, the lowest since he has taken office, and disapproval at 54 percent.

Thirty-nine percent of respondents to a Pew Research Center poll released on Tuesday approve of Mr. Trump’s performance, while 56 percent disapproved.

‘We had Hillary Clinton give Russia 20 percent of the uranium in our country. You know what uranium is, right?’

The claim is not a new one for Mr. Trump, and has been fodder for fact checkerssince September. Behind it is the purchase by Russia’s nuclear power agency of a controlling interest in a Toronto-based company that has assets in the United States, including mills, mines and land used for producing uranium.

Mr. Trump’s claim is incorrect on at least two points.

First, the company’s American assets were equal to 20 percent of the country’s uranium production capacity — not its produced uranium, as Mr. Trump suggested.

Second, Mrs. Clinton was not in a position to approve of or reject the deal herself as secretary of state. Though the State Department did sign off on it, so did eight other federal agencies. It is unclear whether Mrs. Clinton was briefed about or weighed in on the State Department’s decision.

‘I think you have a lower approval rating than Congress. Is that one right?’

Mr. Trump’s instinct to hedge on the news media’s approval rating was right. The news media does not enjoy a great reputation among Americans, according to a variety of polls in recent years, but Congress fares worse.

Gallup’s annual poll of Americans’ confidence in their institutions, the most authoritative on the matter, found that as of June 2016, just 21 percent of Americans had a “great deal” or “quite a lot” of confidence in television news and only 20 percent in newspapers. Congress, by comparison, inspired confidence in just 9 percent.

There is evidence that Congress’s approval rating is on the rise in Gallup’s polling, but there is not more recent data comparing the institutions.

‘Let me tell you about the travel ban. We had a very smooth rollout of the travel ban.’

Mr. Trump went on to say that aside from a federal district judge’s decision to temporarily halt the ban, its rollout had been “perfect.” By most measures, that is far from true.

The order’s announcement and speedy implementation created chaos across the country and around the world. Travelers already in transit were stranded, protests erupted in the United States, and green card holders were initially blocked from re-entering the country before being allowed back in. Several additional judges challenged various aspects of the measure.

Even senior Republicans who agreed with the order’s goals said it had been “poorly implemented” and had sown confusion by being “overly broad.”