Immigration. Because fertility is projected to remain below its replacement-level rate, the projected growth of the U.S. population increasingly stems from net immigration flows. In 2018, net immigration accounted for approximately 48 percent of overall population growth. In 2050, by contrast, projected net immigration accounts for nearly all population growth. CBO’s projection of net immigration in the near term includes the effects of changing economic conditions, heightened travel restrictions, and reduced visa processing capabilities associated with the pandemic. In CBO’s projections, the rate of net annual immigration averages 2.8 immigrants per 1,000 people in the U.S. population over the next 30 years, rising from 1.6 immigrants per 1,000 people in 2020 to 2.9 immigrants per 1,000 people by 2050.

CBO projects net flows for three broad categories of immigrants: legal permanent residents, foreign-born people without legal status, and legal temporary residents.16 Net flows of legal permanent residents constitute the largest category, averaging 790,000 people per year in the first decade of the projection period (2020 to 2030), rising to 870,000 people per year in the third decade (2041 to 2050). The other two categories are much smaller: Net flows of foreign-born people without legal status average 10,000 people per year in the first decade, rising to 130,000 people per year in the third decade. The net flow of legal temporary residents averages 60,000 people per year in the first decade, rising to 80,000 people per year in the third decade. Between 2021 and 2040, immigration is projected to increase as the effects of the pandemic ease and economic conditions are once again an important predictor of net flows of foreign-born people without legal status.

Mortality. Mortality rates are projected to decline (that is, life expectancy is projected to increase) over the next 30 years, on average. That decline in mortality rates is projected to occur even though the number of deaths per 1,000 people in the U.S. population has increased in recent years, because CBO expects the rate of mortality improvement to return to its longer-run trend.17 In the near term, the agency’s projections of mortality incorporate more deaths among people age 55 or older to reflect the effects of the pandemic. Those additional deaths include fatalities directly attributable to the coronavirus as well as increased fatalities attributable to heart disease, diabetes, and pneumonia and other respiratory illnesses; they are partially offset by decreases in fatalities associated with a reduction in accidental deaths. Life expectancy at birth is projected to increase from an average of 79.0 years in the first decade of the projection period to an average of 81.6 years in the third decade. Similarly, life expectancy at age 65 is projected to increase from an average of 19.7 years in the first decade to an average of 21.3 years in the third decade of the period.18