On March 25, 2020, President Trump responded to his administration’s handling of the COVID-19 pandemic by tweeting that the U.S. had undertaken “far more” COVID-19 coronavirus testing than “any other nation,” including South Korea:

Just reported that the United States has done far more “testing” than any other nation, by far! In fact, over an eight day span, the United States now does more testing than what South Korea (which has been a very successful tester) does over an eight week span. Great job! — Donald J. Trump (@realDonaldTrump) March 25, 2020

During a Coronavirus Task Force press briefing from the White House on March 30, a reporter questioned Trump’s claim in that regard, pointing out that the U.S. still lagged behind countries such as South Korea in per capita testing.

Trump responded by asserting, “Look … per capita we have areas of country that’s very large.” He then proclaimed, “I know South Korea better than anybody. It’s a very tight …” before posing the question, “You know how many people are in Seoul” You know how big the city of Seoul is?”

Trump proceeded to answer his own question, stating: “38 million people. That’s bigger than anything we have. 38 million people all tightly wound together. We have vast farmlands, we have vast areas where they don’t have much of a problem … in some cases they have no problem whatsoever”:

A question about per capita testing causes the President to misstate the population of Seoul by around 30 million pic.twitter.com/jyqfCJhlgU — Acyn Torabi (@Acyn) March 30, 2020

Population numbers can vary based on what figures and estimates they’re based upon, and whether a “city” is defined as only the area within a particular city limit or as also encompassing a larger surrounding metropolitan area. However, no reckoning we could find puts the city of Seoul as home to anywhere close to 38 million people.

Multiple sources, including a United Nations report on the world’s cities puts the 2018 population of Seoul (the city) at just under 10 million people, representing a bit under 20% of the country’s entire population:

Estimates for the population of the greater metropolitan Seoul Capital Area encompassing Seoul, Incheon, and Gyeonggi-do put that number at about 25 million, roughly half the entire country’s population:

The population of Seoul in 2016 is estimated at 10.29 million, although this is just the population of the Special City, which has a density of about 17,000 people per square kilometer (45,000/square mile). The sprawling metropolitan area is much larger at 25.6 million.

So Trump was right to suggest that much of South Korea’s population is concentrated in a single area, but the population of that area (Seoul) is still far, far short of his claimed figure of 38 million people. We don’t know the source of that figure, although it closely matches the estimated population of the entire Greater Tokyo Area: