Many Americans moved out of the nation's largest cities during the pandemic to live in suburbs in the southern part of the country, according to the US Census.

New York, Los Angeles, San Francisco and Chicago all have experienced significant population losses during the first year of the pandemic, the US Census Bureau reported March 24.

The New York metropolitan area, which saw an outflow of 385,455 people from 2020 to 2021, tops the list of big cities with the largest population decline. That happened despite the region gaining new residents from abroad and its number of births outpacing deaths during that same time period. 

The nation's most populous city also has experienced an increase in shootings and has endured some high-profile crimes, including against Asian Americans. New York also had some of the US' strictest COVID-19 policies in place.

Phoenix, Arizona, received the most new residents. Its  population grew from 1.4 million people in 2010 to 1.6 million in 2020, a rate of 11.2 percent, according to the Census Bureau. Phoenix grew at the fastest rate among America's biggest cities, vaulting it ahead of Philadelphia to officially become the fifth-biggest city in the US since the last census. 

Population in the Dallas metropolitan area increased by 54,319 and Tampa, Florida, added 42,089 new residents.

"The patterns we've observed in domestic migration shifted in 2021," Dr Christine Hartley, assistant division chief for estimates and projections in the bureau's population division, said in a statement.

The Los Angeles area, which lost 204,776 people, placed second on the list. LA also has seen an increase in crime, with the county sheriff reporting a 137 percent rise in crime in February over the same month in 2021. Los Angeles also has had a controversial COVID-19 school-mask policy that was rescinded on March 18. 

It is closely followed by San Francisco, which was affected by a domestic migration loss of 128,870 people, and Chicago, which lost 106,897 residents. 

In addition, other metropolitan areas, such as San Jose, California, Boston, Miami and Washington DC regions, also lost tens of thousands of residents.

While people are leaving costly, densely populated metropolitan centers, an increasing number of them are also migrating into suburbs or smaller towns, which offer a lower cost of living and a lifestyle change.

"Even though over time we've seen a higher number of counties with natural decrease and net international migration continuing to decline, in the past year, the contribution of domestic migration counteracted these trends so there were actually more counties growing than losing population," Hartley said.  

Those changes resulted in population increases in 1,822 counties, or 58 percent of total US counties; 41.8 percent, or 1,313 counties, saw a decline in residents; eight counties, or 0.3 percent, saw no change in their populations, the Census Bureau reported.

Texas is the home to five of the top 10 counties that expanded their populations in 2021, which together gained 145,663 people. 

Moreover, the latest census indicated that growth in micro areas is accelerating. This is different than in the past when metropolitan areas usually grow at a faster rate than their micropolitan counterparts. Micropolitan areas are defined as urban centers with a population of at least 10,000 but fewer than 50,000 people.

Sixty-five percent, or 251 of the metro areas experienced a population increase between 2020 and 2021; 52.9 percent, or 287 out of 543 micro areas reported gains. Kalispell, Montana, Jefferson, Georgia, and Bozeman, Montana, were the top three micro areas that saw the greatest increases in population.

Demographer William Frey told The Associated Press that he believes the change in population trends is temporary. It is taking place as many people are relocating during the pandemic when working remotely becomes an option, he said.

"There is clearly a dispersion, but I think it's a blip," said Frey, senior fellow at the Brookings Institution's metropolitan policy program Brookings Metro.

"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. That is going to come back. With the natural decrease, we will go back to normal," Frey told the AP.

The data released Thursday covered 3,143 counties, 384 of the nation's metropolitan statistical areas and 543 micropolitan statistical areas.