As we learned last week, the U.S. added 275,000 jobs in February, not far from the number it added in February the prior year — 287,000. In fact, the economy has been creating jobs like nobody’s business, month after month, for a few years now.

But there’s a mystery. The unemployment rate actually ticked up last month. Wage growth has slowed down, and so has inflation — things you would not expect from a labor market that’s still driving full speed ahead. The explanation touches on one of the most highly charged political debates of the moment.

For many economists, something about this booming job market was not adding up.

“Where are all these jobs coming from?” asked Torsten Slok, chief economist at Apollo Global Management. “Why is it the economy’s creating so many jobs without accelerating wage inflation?”

The short answer is that the U.S. has been importing economic capacity.

“Immigration has played a very important role in why job growth continues to be so strong,” he said.

There has been a wave of immigration — legal and not — since 2022. According to the Congressional Budget Office, 5.9 million people migrated to the U.S. in that time, more than 3 million of them in 2023. A large number came across the southern border, said Julia Gelatt, associate director of the U.S. immigration policy program at the Migration Policy Institute.

“There’s the really strong draw factor of our booming economy. We recovered from the pandemic recession much more quickly and strongly than many other countries, especially in the Americas,” she said.

The U.S. is maxing out its legal immigration pathways, but even undocumented people are finding employment, said Madeline Zavodny, professor of economics at the University of North Florida.

“The popular perception you have is, ‘Oh, they’re illegal immigrants. They’re going to be on the streets’ and all of this,” she said. “But it does look like a lot of them are working.”

And working on the books to show up in the data. Tara Watson, who directs the Center for Economic Security and Opportunity at the Brookings Institution, said all this extra labor has basically helped fix shortages.

“Immigrants are helping to supply some of the goods and services that people have been looking for as they come out of the COVID era,” she said.

They’ve also filled shortages of workers in certain fields, helping to balance out an overheated labor market. In effect, she said, immigration has helped bring down inflation.