In fact, their data showed, the number of births in 14 states would have dropped between 1990 and 2015 — were it not for children born to immigrant mothers.

Overall, the number of births increased in half of the states over that time period and decreased in half. (Birthrates in D.C. also declined.)

Looking only at mothers who were born in the United States, though, rates in 39 states declined.

We can make that shift more obvious by animating the transition between the two: Change in the number of births to just U.S.-born mothers and then the overall change.

In only two states was the change in the number of births over that period lower once births to immigrant mothers were included. In other words, change in the total number of births from U.S.-born mothers between 1990 and 2015 was higher than the change in the number of births overall. In every other state, including immigrant mothers made that difference increase.

Earlier this year, we looked at a claim by then-adviser to President Trump Stephen K. Bannon who argued that a fifth of the country’s population had immigrated here. That’s not true, but the percentage of the population that is foreign-born has increased and is projected to increase further.

The babies of those immigrants, though, are American citizens. As the number of first-generation immigrants increases, so, too, will the number of second-generation immigrants.