COVID-19 caused a major population shift in the U.S., most dramatically in cities that felt the brunt of pandemic conditions, according to the Census Bureau.

Overall, more than 73% of U.S. counties experienced a natural decrease in their population. When compared to past percentages, counties in the U.S. experienced a 45.5% natural decline in 2019 and a 55.5% decline in 2020.

The U.S. census bureau acknowledged that “in 2021, fewer births, an aging population and increased mortality — intensified by the COVID-19 pandemic — contributed to a rise in natural decrease.”

Specifically, population declines in major cities are attributed to pandemic conditions, which caused “a shift from larger, more populous counties to medium and smaller ones.” In the U.S., "micropolitan" areas “grew slightly faster than U.S. metro areas.”

“This is a departure from past trends when metro areas typically grew at a faster rate than micro areas,” the U.S. Census Bureau said in a news release.

The conditions created during the pandemic led people to flee the cities and head to more suburban or rural areas, the report shows. The trend is the result of remote work becoming more popular during the pandemic and more severe COVID conditions in larger cities causing people to flee.

“We’re at one of the lowest levels of immigration in a long, long time, and that affects big metros like New York, Los Angeles, and Chicago," said demographer William Frey, a senior fellow at the Brookings Institution’s Brookings Metro, told AP News. "That is going to come back. With the natural decrease, we will go back to normal.”

The pandemic has changed the trends of where people move in the U.S., with a preference towards micropolitan areas rather than metropolitan areas.

“The patterns we’ve observed in domestic migration shifted in 2021,” said Dr. Christine Hartley, assistant division chief for estimates and projections in the Census Bureau’s Population Division. “In the past year, the contribution of domestic migration counteracted . . . trends so there were actually more counties growing than losing population.”

The pandemic also has disrupted the ability to determine trends, however, which will affect the ability to predict them in the future.

Children are seen outside a coronavirus disease (COVID-19) testing site in Brooklyn, New York, U.S., January 12, 2022.
Children are seen outside a coronavirus disease (COVID-19) testing site in Brooklyn, New York, U.S., January 12, 2022. Reuters / BRENDAN MCDERMID