How Much Slower Would the U.S. Grow Without Immigration? In Many Places, a Lot

As the United States debates the right levels of immigration — and whether, as President Donald Trump suggested, there is room for much more of it — new census data shows that international migration is keeping population growth above water in much of the country.

Although international migration dropped in 2017 and 2018, it accounted for nearly half of overall U.S. population growth in 2018 as birthrates declined and death rates rose.

International migration helped rural counties record their second straight year of growth, according to local population estimates for 2018 that the Census Bureau released Thursday. And immigrants bolstered urban counties that have been losing residents to more affordable areas. Even so, the three largest metro areas in America — New York, Los Angeles and Chicago — all shrank slightly.

Without these international moves, 44% of the nation’s population would be in shrinking counties, instead of the current 27%. Dense urban counties and sparse rural areas, despite typically being on opposite sides of the political spectrum, share economic concerns related to population decline.

In rural America in particular, shrinking populations can lead to a vicious cycle, causing local businesses to fail and young people to leave in search of opportunity, saddling those who remain with a smaller tax base for local services.

Some tiny communities grew as much from international migration, in percentage terms, as large global magnets did.

The metro areas where international migration contributed the most growth in 2018 include the big, diverse metros of Miami; Orlando, Florida; and San Jose, California. But that growth was rivaled by college towns like Brookings (South Dakota State), Pullman (Washington State), Ames (Iowa State), and Champaign-Urbana (University of Illinois) — as well as by the meatpacking center of Huron, South Dakota, and the Transcendental Meditation center of Fairfield, Iowa.

Although that’s an eclectic list of places, there’s a clear geographic pattern. International migration contributes to population growth more in larger metros than in smaller ones or in rural areas— and most of all in the dense urban counties of large metros. These urban counties lose population as a result of domestic migration because moves within the United States tend to be out of dense, urban counties and into suburbs or smaller metros.

International migration — which includes immigration and other international moves regardless of citizenship or country of birth — is increasingly important for population growth in the highest-density counties of large metros.

The growth in 2018 for these areas slowed to the lowest rate since 2006, just before the giant housing bust. These urban counties rebounded in the years that followed, reaching a peak in 2011 and 2012 that looked like a demographic reversal of the long-running suburbanization of America. But then urban county growth slowed, and in fact had not been as impressive as originally thought. The latest census data has revised earlier urban growth estimates downward.

Americans are leaving urban counties overall as rising home prices and inadequate construction push people to more affordable suburban counties, midsize metros and smaller metros.

In all, nine of the 51 metros of a million-plus lost people in 2018. An additional 10 large metros — including Miami, Boston and San Francisco — would have lost population if not for international migration. And, for the first time since 2007, the rate of population growth in large metros slipped below that of midsize metros.

But it’s not just big cities. Counties outside metropolitan areas — mostly small towns and rural areas — draw and lose roughly even numbers from domestic migration. But because of their older local populations, deaths nearly equaled births in nonmetropolitan counties. Even though international migration contributed less to population growth in rural counties than in other places, international migration contributed more in rural counties than either domestic migration or natural increase did.

The latest estimates offer a silver lining for lagging rural America; 2018 showed population growth for the second year in a row, and at a faster rate than in 2017. This uptick in rural growth meant that the share of Americans living in shrinking counties — which rose sharply to 30% in 2017 from 14% in 2010 — fell back to 27% in 2018. The assist, again, came from international migration.