Though the foreign-born fraction has risen to its late-19th-century levels, the net migration rate is just half the level that prevailed around 1900 (Blau and Mackie 2017). With declining native-born population growth in recent years, even a diminished level of net migration has been enough to raise the foreign-born fraction (see figure 2a).
Figure 2b shows that recent growth in the number of prime-age children of immigrants has continued at more than 3 percent, supporting overall U.S. population growth. By contrast, the population growth rate of prime-age children of native parents has fallen from an average of 0.2 percent over the 1995–2005 period to an average of –0.5 percent over the 2006–17 period. The population growth of first-generation immigrants remains relatively high—1.8 percent on average from 2006 to 2017—but has fallen as net migration has slowed. Thus, the continued rise of the foreign-born share of the population since 1990 does not reflect a surge in immigration but rather a slowing migration rate combined with slowing growth in the population of children of natives.
From 1960 to 2016 the U.S. total fertility rate fell from 3.65 to 1.80 (World Bank n.d.). Demographers and economists believe that this decline was driven by a collection of factors, including enhanced access to contraceptive technology, changing norms, and the rising opportunity cost of raising children (Bailey 2010). As women’s labor market opportunities improve, child-rearing becomes relatively more expensive. Feyrer, Sacerdote, and Stern (2008) note that in countries where women have outside options but men share little of the child-care responsibilities, fertility has fallen even more.
Population growth is important for both fiscal stability and robust economic growth. Social Security and Medicare become more difficult to fund as the working-age population declines relative to the elderly population. (See fact 11 for a broader discussion of immigrants’ fiscal impacts.) Moreover, overall economic growth depends to an important extent on a growing labor force (see fact 8).