The U.S. Census Bureau’s 2020 census results show that less than half of all counties across the nation experienced population growth over the past decade. Large urban areas, specifically in the South and West, grew considerably over the decade, while most rural areas experienced declines. Overall, between 2010 and 2020, the United States population grew by 7.4 percent (about 22 million residents). These new estimates also depict a diversifying, multiracial U.S. population.

Over half of the nation’s population growth in the last decade was concentrated in just 80 counties. On the other hand, population decline was widespread throughout over half of all counties (1,628 counties), 87 percent of which were small counties (those with populations less than 50,000). With more than 10 million residents, Los Angeles County, Calif., is still the largest county in the nation. New York City, N.Y. (5 boroughs consolidated), Cook County, Ill., Harris County, Texas and Maricopa County, Ariz., rounded out the top five largest counties in 2020. The fastest-growing county over the past decade was McKenzie County, N.D., which had a population increase of 131.2 percent. Williams County, N.D. and Hays County, Texas were the second and third fastest-growing counties, gaining 83 percent and 53 percent more residents, respectively.

Less than half of all counties (1,440 counties) experienced gains in population between 2010 and 2020, representing 46.9 percent of counties. Among large counties (those with over 500,000 residents), the most significant increase in population over the decade occurred in Harris County, Texas, which gained over 638,000 residents. In addition, New York City, N.Y., Maricopa County, Ariz., King County, Wash. and Clark County, Nev. experienced substantial population growth. Large counties accounted for nearly half (49.6 percent) of all county residents in 2020, up 0.9 percent from 2010. Medium-sized counties (those with populations between 50,000 and 500,000) accounted for 38.3 percent of all county residents, a 0.2 percent increase from 2010. Conversely, small counties experienced a decrease in population. These counties now represent 12.1 percent of all county residents, down from 13.2 percent in 2010.

The most significant gains in population over the last decade occurred in the southern and western regions of the country. Four hundred nine counties gained 10,000 residents or more; 207 of those counties were in the South and 93 were in the West. Southern counties gained over 11.5 million residents between 2010 and 2020, the most growth among the four Census regions. With a population gain of over 6.8 million residents, Western counties saw the second-most increase over the decade. Texas counties gained the most residents of any state, ahead of Florida and California.

The diversity profile of the nation is changing, with the share of white residents decreasing as the shares of Black, Hispanic and people of other races/ethnicities grow. Heading into the recent decennial census, the U.S. Census Bureau improved and updated questions to capture the racial and ethnic composition of the country more accurately. These changes resulted in two questions, one for Hispanic or Latino origin and one to indicate an individual’s race. As a result, the 2020 figures show that 62.1 million people (18.7 percent of the U.S. population) identified as Hispanic or Latino, compared to 50.5 million (or 16.3 percent of the U.S. population) in 2010.[i] The “White alone” racial category included 204.3 million people, representing a decrease of 8.6 percent since 2010. The “Black or African American alone” population grew from 38.9 million in 2010 to 41.1 million in 2020, representing 12.4 percent of the United States population.[ii] In addition, the Census allows individuals to mark more than one race. In 2020, the percentage of people who reported multiple races was 10.2 percent (33.8 million people). In 2010, just 9 million people (2.9 percent of the U.S. population) reported multiple races.[iii] Alongside demographic shifts, the altered question design also helps explain these changes in racial and ethnic distributions.

Changes in demographic composition occurred more quickly in some counties than in others. In 2010, 317 counties were majority people of color (those identifying as Hispanic, Black or African American, Asian, American Indian and Alaska Native, Native Hawaiian and Other Pacific Islander or Some Other race), while in 2020, this figure jumped to 375 counties. Out of these 375 counties, 68 percent are in the South. Within the last decade, 61 counties in 20 states became majority people of color (3 counties were majority people of color in 2010 but had majority white residents in 2020). Four of the five counties with the highest percentage of residents of color are in Texas (Starr, Maverick, Webb and Zapata Counties), along with Oglala Lakota County, S.D. Among large counties, Hidalgo County, Texas, Prince George’s County, Md., El Paso County, Texas, Miami-Dade County, Fla. and Honolulu City and County, Hawaii each have the highest percentage of residents of color (ranging from 93.8 percent to 82.7 percent). Of these 375 counties, 255 are in the South, 86 in the West, 23 in the Midwest and 11 in the Northeast.

The U.S. Census also collects data on housing units, including occupied and vacant units. Vacancy rates can serve as an indication of how tight the housing market is in each county. In counties with low vacancy rates, competition is higher, leading to higher rents or home prices. Prince William County, Va. had the lowest vacancy rate at 3 percent, just ahead of Dakota County, Minn. and Davis County, Utah at 3.1 percent and 3.2 percent, respectively. These are all medium-sized counties. Among large counties, Stanislaus County, Calif. had the lowest vacancy rate at 3.5 percent. Fairfax County, Va., Contra Costa County, Calif., Bucks County, Pa. and Sacramento County, Calif. were amongst the top five large counties with the lowest vacancy rates. Additionally, 7 of the top 10 large counties with the lowest vacancy rates are in the West.

The three counties with the highest vacancy rates were Hinsdale County, Colo. (71.8 percent), Rich County, Utah (71.4 percent), and Forest County, Pa. (70.7 percent), all of which are small counties. Among large counties, Lee County, Fla. has the highest vacancy rate at 23.5 percent, ahead of Ocean County, N.J., Volusia County, Fla., Baltimore City, Md. and Pinellas County, Fla. Higher vacancy rates indicate flexibility within the housing market and may suggest housing prices will trend down over time.

The 2020 U.S. Census presents essential information on how the U.S. population is growing and changing. It plays a role in redistricting, apportionment for the U.S. House of Representatives and funding for programs and services. Over the past decade, the population has grown, led mainly by urban growth in the West and South and Hispanic or Latino populations.

Check out NACo’s County Explorer tool for more county-level data and profiles that offer informative, statistical summaries. Visit www.Explorer.NACo.org.

Note: County-level analysis is based on 3,069 counties with active county governments. Thus, Puerto Rico, Connecticut, Rhode Island and portions of Alaska and Massachusetts are excluded since they do not have active county governments. Independent cities in Virginia are also excluded from the analysis.

This article was prepared by Dina Pinsky, Research Intern, Stacy Nakintu, Research & Data Analyst and Ricardo Aguilar, Associate Director, Data Analytics.