Maricopa County was the fastest-growing county in the United States last year. The U.S Census Bureau broke down those gains by race between 2020 and 2021.

Maricopa County saw the largest increase in its white population compared to every other county. 

And the Phoenix-Mesa-Chandler metro area saw the largest increase of American Indian or Alaskan Native population.

Maricopa also had some of the largest growth in Black and Hispanic residents last year.

Kings County in New York saw the biggest decline of Black residents, while Los Angeles County saw the biggest declines in white, Asian and Hispanic Residents. Los Angeles County is the most populous county in the United States. 

The data does not reflect changes between the summer of 2021 and now. 

Eight of the 10 largest cities in the U.S. lost population during the first year of the pandemic, with New York, Los Angeles and Chicago leading the way. The counties at the heart of those cities, Los Angeles, New York and Cook counties, also lost the most residents from mid-2020 to mid-2021, according to Thursday's estimates.

An analysis by the Census Bureau released Thursday said that the reason for the declines in the central counties of these large metro areas was due to the flight of young adults in their early 20s to mid-30s during the first year of the pandemic since they were able to work remotely in lower-cost areas with other quality of life improvements.

EDITOR'S NOTE: The story has been updated to correct the headline.