Census 2020: First results show near historically low population growth and a first-ever congressional seat loss for California

Census 2020
Editor's note:

We corrected 2010-2020 data on Table 1 and Florida data on Figure 4 in this research brief on April 27, 2021.

This report is part of a series by the author on the results of the 2020 census.

The first results of the 2020 census are finally here, definitively showing that the 2010s saw the second-lowest population growth in the nation’s history. Among all 50 states, 37 grew more slowly in the 2010s than in the previous decade, and three states lost population—the largest number of such states since the 1980s. The constitutionally mandated reapportionment of members of Congress based on the 2020 census indicates a reallocation of seven seats across various states—most notably, the first-ever loss of a seat for California.

The 2020 census results are released in several stages. This first release of total populations for states was scheduled to occur last December. However, collection and processing issues associated with the COVID-19 pandemic and natural disasters delayed the release until now.

The purpose of this first set of numbers, articulated in the U.S. Constitution, is to provide the basis for allocating members of the House of Representatives across states, taking into account population changes that have occurred since the prior census. At the same time, these numbers provide a definitive assessment of how populations across each state and the nation have shifted over the prior decade.

Below are key findings from the new census data associated with national, regional, and state populations, as well as the reapportionment of seats in the House of Representatives.

The 2010s saw the second-lowest population growth in U.S. history

The 331,449,281 U.S. residents counted in the 2020 census represent a population increase of 7.4% from the 2010 count of 308,745,538. This is the second-smallest decade-long growth rate since the first census was taken in 1790—only slightly higher than the 7.3% growth rate from the 1930s in the aftermath of the Great Depression (Download Table A). It is roughly half the 13.2% growth rate of the 1990s, when immigration was high and the last part of the millennial generation was born.


The 2010s registered declines in the number of births, increases in the number of deaths, and lower immigration levels. Immigration was reduced due to federal restrictions that led to a decline in the noncitizen foreign-born population. And low natural increase levels (fewer births, more deaths) reflect, in part, delays in marriage and childbearing among the economically hard-hit millennial generation, and a rise in drug- and pandemic-related deaths. Meanwhile, the U.S. population continues to age, and Census Bureau projections show that this will further result in lower levels of natural increase. This suggests that the nation will need to increase immigration to keep future growth rates from falling even more starkly.

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Most states showed slowdowns in growth

The low rate of national population growth is reflected in the slow growth or population declines across states. Three states lost population from 2010 to 2020: West Virginia, Mississippi, and Illinois. This is the highest number of population-losing states since the 1980s. In the prior two decades, only one state (Michigan, from 2000 to 2010) lost population (Download Table B).

Table 1

West Virginia registered the greatest rate of 2010-to-2020 population loss (3.2%) and the largest numeric loss (59,000) (Download Table C). West Virginia’s aging population had more deaths than births, and the state saw accelerated out-migration during the 2010s.

Thirty-seven states showed lower growth over the 2010-to-2020 decade than in the previous decade, and all but three exhibited smaller growth rates than in the high-flying 1990s. One of the 13 states that grew faster in the 2010s is North Dakota, where growth rose to 15.8% (up from 4.7%), due largely to in-migration during the energy boom there in the early part of the decade.

At the high end for growth rates from 2010 to 2020 are several western states, along with Texas, Florida, and North Dakota. Among these are Utah, Idaho, Nevada, and Arizona—states which also saw high growth in the two prior decades. Of this group, Nevada showed the biggest growth slowdown (from 66% in 1990 to 2010 to 15% in 2010 to 2020), reflecting the early-decade housing crunch resulting from the Great Recession.

More noteworthy is the reduced growth for the West’s (and nation’s) largest state: California. The Golden State grew by only 6.1% from 2010 to 2020—the lowest growth rate in its history. California’s growth slowdown reflects reduced immigration from abroad as well as rising out-migration, especially to other states in the West.

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Washington, DC’s high growth rate could be emblematic of other cities

One area—not a state—which did well growth-wise in the last decade is Washington, D.C. The District registered an 14.6% growth rate from 2010 to 2020, far surpassing its 5.2% growth from 2000 to 2010, which had followed population losses in each of the previous five decades (Download Table B). Like other major cities, Washington, D.C. benefitted from early-decade gains as young-adult millennials flocked to cities due to stagnating post-Great Recession housing and labor markets in suburbs and smaller-sized places.

While it is true that early-decade gains in the District and other cities shrank as suburban growth picked up, those early growth levels propped up total decade growth for most cities.   When the 2020 census results are released for other cities later this year, it is likely that many of them will show improved growth for 2010 to 2020 compared with the previous decade, following Washington, D.C.’s pattern.

Sun Belt states now comprise 62% of the nation’s population

The slow national growth of the 2010s came alongside an increasing population shift to the nation’s South and West “Sun Belt” regions. Just over 50 years ago, the 1970 census showed that less than half (48%) of the U.S. population resided in the South and West. The West housed just 17% of the population then, and the South’s 31% was only slightly greater than the Midwest’s 28%.


Since then, the Sun Belt’s share of the U.S. population rose to 62%, with approximately 7% gains in both the West and South. The population shares of the Midwest and Northeast, meanwhile, each fell by 7%.

The 2020 census results show that the South now houses a decided plurality (38%) of the U.S. population. And over the 50-year period between 1970 and 2020, the Northeast and West populations switched positions: the Northeast’s share declined from 24% to 17% as the West’s share rose from 17% to 24% (Download Table D).

The South and West’s 2010s population growth of 10.2% and 9.2%, respectively, far outpaced the Midwest (3.1%) and Northeast (4.1%). Moreover, several Sun Belt states improved their population size rankings over the decade: Florida overtook New York to become the third-largest state; Georgia and North Carolina overtook Michigan to become the eighth- and ninth-largest states; and Arizona overtook Massachusetts and Indiana to become the 14th-largest state, among other changes (Download Table C).

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Seven House of Representatives seats change states, including a loss for California

The reason why the Constitution mandates a decennial census is to allocate the number of members each state sends to the House of Representatives—which, since 1920, contains 435 seats. Thus, when a new census is taken, some seats are reapportioned to take into account changing state population sizes. When this occurs, some states gain seats while others lose them.

Table 2

On the basis of the 2020 census, only seven seats will change states—the smallest number in recent history (Download Table E). All of the states gaining seats are in the South and West: Texas (which is gaining two seats), Florida, Colorado, Montana, Oregon, and North Carolina.

Five of the states losing seats are located in the Midwest and Northeast: Illinois, Michigan, Ohio, New York, and Pennsylvania. The other two states losing seats are West Virginia and California.


The latter is noteworthy from a historical standpoint. Prior to this, California had never lost a congressional seat from reapportionment. It gained seats (often multiple seats) from 1920 to 2000, when it reached its peak number of representatives at 53—the largest state delegation in the House. After the 2010 census, it neither gained nor lost seats, and now, for the first time, its delegation will become reduced.

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Electoral College gains may no longer favor Republicans

The new reapportionment pattern puts recent Sun Belt population gains in historical perspective. Over the 100-year period from 1920 to 2020, three Sun Belt states—California, Florida, and Texas—have gained the most congressional seats due to reapportionment, with additions of 41, 24, and 20 seats, respectively (Download Table F).

However, in the most recent three decades, many new Sun Belt population gains have occurred in the interior parts of the West and South, as migrants and new immigrants began to disperse to other states in these regions. The cumulative shifts in seats over this period have not only given multiple seats to Texas and Florida but also to Arizona, Georgia, Colorado, Nevada, and North Carolina.


The political dimension of this shift should not go unnoticed, as reapportionment has increased the Electoral College clout of these particular states. As recently as 2000, each of these seat-gaining Sun Belt states voted fairly consistently for Republican candidates in presidential elections. However, the demographics of each have changed in ways that already or may soon shift each of them to the Democratic column.

So, while the reapportionment additions to Sun Belt states have long been seen to favor Republican candidates in the Electoral College, this is not as likely to be the case for future presidential elections.

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Looking ahead to the next decade

These first results from the 2020 census show a nation that is growing as tepidly as any time in its history. While some of this growth slowdown may be related to the impacts of the Great Recession, reduced immigration, and the COVID-19 pandemic (which started just weeks before the Census Bureau’s enumeration began), much of it reflects the continuing aging of the U.S. population, which has led to fewer births and more deaths than seen in the past.

Beneath this national context, most states registered population growth declines or losses, with continued (but modest) shifts to the West and South, including to interior parts of these regions. The latter are reflected in the new congressional reapportionment, which favors the Sun Belt hot spots of Texas and Florida, but also western states near California as residents migrate out of the state.

We will have to wait until later 2020 census releases to learn how and where the nation’s age and race-ethnic groups have shifted over the past decade. We can expect to see an aging population nationally and in most parts of the country, as the large baby boomer generation continued to enter its senior years. And even with the slowdown in immigration, it is likely that the nation’s population became more racially diverse, particularly among children and young adults.

As we digest these and later results of the 2020 census, it is apparent that the United States is becoming a more demographically stagnant nation. How we adapt in the post-pandemic period in terms of childbearing, movement across states, and toward adopting a reasoned immigration policy will determine what kind of country we will become, both demographically and economically, in the decade ahead.

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