We await the April 1, 2020 census datapoint, but so far it looks like the 2010s will go down in U.S. history as the decade with the slowest population growth. In the years between April 1, 2010 and July 1, 2019, the U.S. population grew by just 6.3%, according to the Census Bureau's newly released population estimates for 2019. When the April 1, 2020 census count is released this year, the growth rate of the 2010s is likely to remain below the current record low of 7.3% recorded in the 1930s.

U.S. population growth by decade has been slowing since the 1950s. During the 1950s, the population grew by 18.5% – more than double the growth of the 1930s – coinciding with the birth of the Baby Boom generation. In every decade since, population growth has been slower than in the previous decade, with the exception of the 1990s...

Percent change in U.S. population by decade

2010 to 2019: 6.3% (incomplete data)
2000 to 2010: 9.7%
1990 to 2000: 13.1%
1980 to 1990: 9.8%
1970 to 1980: 11.4%
1960 to 1970: 13.4%
1950 to 1960: 18.5%
1940 to 1950: 14.5%
1930 to 1940: 7.3% (record low)

Note: Percent changes by decade are calculated using April 1 census counts except for 2010 to 2019, which is the percent change from April 1, 2010 to July 1, 2019.

There are two reasons for the slow rate of population growth during this decade. The ongoing baby bust is one reason, with the fertility rate at a record low. The annual rate of natural increase (births minus deaths) fell from 4.7 to just 2.9 per 1,000 population from 2010 to 2019. The number of people added to the population each year through natural increase fell from 1.5 million between 2010 and 2011 to just 957,000 between 2018 and 2019.

Falling net migration (immigrants minus emigrants) is the other factor that has resulted in what is likely to be the slowest decade of population growth in U.S. history. The annual rate of net migration fell from 2.5 to 1.8 per 1,000 population from 2010 to 2019. The population gain from net migration during this decade peaked at more than 1 million in 2015 and 2016. But between 2018 and 2019, a net of only 595,000 migrants were added to the population.

Source: Census Bureau, National Population Totals and Components of Change: 2010—2019