Group of neighbors enjoy one another’s company

The U.S. Population Is Growing Older, and the Gender Gap in Life Expectancy Is Narrowing

The current growth of the population ages 65 and older is unprecedented in U.S. history and has important implications for policymakers.

Although government programs such as Social Security, Medicare, and Medicaid have helped reduce poverty and improve the health of the older population, current projections indicate that these programs—as currently implemented—are not sustainable.1 The increasing costs of providing for an older population may reduce public spending for other groups, including young families with children. The 2020 Census will provide vital information about the age structure of the U.S. population—including the number of men and women in different age groups and the share of older adults across states and local communities—to help policymakers meet the needs of their constituents.

The number of people ages 65 and older in the United States has increased steadily during the past century, and growth has accelerated since 2011, when baby boomers first started to turn 65 (see Figure 1). Between 2020 and 2060, the number of older adults is projected to increase by 69 percent, from 56.0 million to 94.7 million. Although much smaller in total size, the number of people ages 85 and older is projected to nearly triple from 6.7 million in 2020 to 19.0 million by 2060.

Recent declines in fertility and immigration have slowed growth in the share of children in the population and accelerated population aging. In 2008, U.S. Census Bureau projections showed the number and share of children exceeding that of the older population every year through 2050, while the most recent projections (2017) show the number and share of the older population surpassing that of children by 2034.2 The Census Bureau projects that in 2020, children will make up 22 percent of the U.S. population—the lowest recorded share in U.S. history. By 2060, the share of children in the population is projected to drop even further, to around 20 percent. During that same period, the share of the population ages 65 and older is projected to increase from 17 percent to 23 percent.

Figure 1. U.S. Population by Age Group (millions), 1900 to 2060


Source: U.S. Census Bureau, decennial censuses and vintage 2017 population projections (2020-2060).

The number of centenarians, or people age 100 or older, has also increased from around 32,000 in 1980 to more than 53,000 by 2010. In 2020, it is projected that the older adult population could include 92,000 centenarians, and the number could increase to nearly 600,000 by 2060.

Figure 2 shows the transformation of the U.S. population age structure from 1980 to 2060. The pyramid for 1980 clearly shows the effects of changing fertility rates during the 20th century, with the baby boom cohort—persons born between 1946 and 1964—reflected in the large share of the population ages 15 to 34. By 2020, surviving baby boomers will dominate the 55-to-74 age group, and the pyramid will begin to look more cylindrical. This trend is projected to continue through 2060, when there will be a relatively large share of men and women ages 85 and older. In fact, women ages 85 and older are projected to make up 2.9 percent of the total U.S. population in 2060—a larger share than that of females in the 0-to-4 age group (2.7 percent).

Figure 2: The U.S. Population Is Shifting to Older Age Groups

Population pyramid gif

U.S. Population by Age and Sex (%), 1960 to 2060

Source: PRB analysis of data from the U.S. Census Bureau.

Three demographic trends account for changes in the age structure of the U.S. population in recent decades. First, a shift toward smaller families began in the late 1960s. During the baby boom, the total fertility rate (TFR), or the average number of lifetime births per woman, peaked at over 3.5. But by the mid-1970s, the TFR had dropped to just 1.7—the lowest level ever recorded in the United States. Second, increases in life expectancy—an estimate of the average number of years of life remaining at a particular age—have led to a growing population of older adults relative to those in younger age groups. Between 1980 and 2016, average life expectancy at birth increased from 73.7 to 78.6 years.3

Third, declines in immigration have reduced population momentum by limiting the number of young adults of reproductive age who are moving to the United States and starting families. The number of women ages 25 to 44 increased by 35 percent (from 31.8 million to 42.9 million) from 1980 to 2017, but is projected to increase by only 15 percent between 2017 and 2060 (to 49.3 million). Slower growth in the number of women of reproductive age, in combination with falling fertility rates, is resulting in fewer births and children relative to the number of older adults in the population.

The future size of the older population relative to the population of children and working-age adults will depend in part on trends in immigration. The latest projections from the Census Bureau assume that net international migration (the number of immigrants minus the number of emigrants) will peak at around 1.1 million per year by 2060.4 But if future immigration levels are higher than the Census Bureau projects, the number of older adults could be reduced relative to those in younger age groups.

The Sex Ratio at Older Ages Is Narrowing

The number of males per 100 females in a population, or the sex ratio, can vary depending on sex differences in health risks and behaviors, mortality rates, immigration patterns, and other factors. In the United States, as in other countries, newborn males outnumber newborn females, while females are more likely than males to reach older ages. The projected U.S. sex ratio in 2020 favors women slightly, at 97 men per 100 women, but patterns vary across age groups. The Census Bureau projects that the sex ratio in 2020 will be 104 for children under age 18, but only 56 for adults ages 85 and older (see Figure 3). Among centenarians, there will be only 30 men per 100 women, according to the Census Bureau’s projections for 2020.

Women live longer on average than men in the United States and in nearly every country in the world. But in the United States, the gender gap among older adults has shifted during the past century. At the turn of the 20th century, there were 102 older men (ages 65 and older) per 100 older women. By 1990, the sex ratio among the older adult population had fallen to 67, its lowest recorded level.5 Since then, the sex ratio among adults ages 65 and older has rebounded and is projected to increase to 81 by 2020 and to 86 by 2060.

Researchers have linked U.S. trends in the gender gap in life expectancy at older ages to male and female patterns of smoking, which increase the risk of an earlier death from lung cancer, heart disease, chronic obstructive pulmonary disease, and stroke.6 During the first half of the 20th century, smoking prevalence rates among men and women
converged, as men’s rates declined from their earlier peaks and women’s rates increased, leading to a rise in smoking-related deaths among women relative to men.7 Smoking prevalence peaked among women born in the early 1940s, whereas prevalence rates peaked for men born in the 1910s. The result has been a steady reduction in smoking-related deaths among older men and an increase in deaths among older women.

Figure 3. The Number of Males per 100 Females Declines Sharply at Older Ages

bar chart

Projected Sex Ratio by Age Group, 2020

Source: U.S. Census Bureau, vintage 2017 population projections for 2020.

A changing sex ratio has implications for caregiving in old age. Historically, older adults have relied heavily on family caregivers to provide support and care when they needed assistance. However, fewer children and high divorce rates among baby boomers mean that more may live alone in old age without either the financial and social support or informal caregiving provided by a spouse or child. Spousal care could potentially help fill this gap; with more men surviving to old age, more potential partners may be available to provide informal care for older adults.

Support Ratios for Older Adults and Children Are Shifting

Policymakers are concerned about the growth in the population ages 65 and older, and whether the U.S. workforce will be large enough to support future spending on Social Security and Medicare. One way to measure this support is through the old-age support ratio—the number of working-age adults ages 18 to 64 for every person age 65 or older. The old-age support ratio is just an approximation because some people stop working before they reach age 65, and a growing share of adults are continuing to work into their late 60s and early 70s. In 1960, there were 6.0 working-age adults for every person age 65 or older.8 The ratio is projected to drop to 3.6 by 2020 and even further—to 2.4—by 2060. This projected decrease in the number of workers relative to those who are retired or can no longer work could have implications for the old-age support systems currently in place.

While the old-age support ratio has decreased in recent decades, the support ratio for children—the number of working-age adults per child under age 18—has increased. Between 1960 and 2010, the ratio has gradually risen from 1.5 to 2.6 working-age adults per child (see Figure 4). By 2040, the support ratio for children (2.8) is projected to exceed the old-age support ratio (2.7) for the first time in U.S. history. These shifting support ratios may lead to higher levels of public spending on the health and economic well-being of older adults, relative to young families and children.

Figure 4. The Number of Working-Age Adults per Older Adult Has Fallen Dramatically

Bar chart

Number of Working-Age Adults (Ages 18-64) per Older Adults (Ages 65+) and Child (Under Age 18), 1960 to 2020

Note: The old-age support ratio is the number of adults ages 18 to 24 per adult age 65 or older. The support ratio for children is the number of adults ages 18 to 64 per child under age 18.
Source: U.S. Census Bureau, decennial censuses and vintage 2017 population projections (2020-2060).

While the solvency of Social Security benefits depends on the old-age support ratio at the national level, the provision of many programs and services for older adults occurs at the state and local levels, where low old-age support ratios may already be raising challenges. Nationwide, there were about four working-age adults (ages 18 to 64) per person age 65 or older in 2017. However, in roughly 40 percent of U.S. counties, the old-age support ratio has already fallen below three working-age adults per older adult. Many of these counties are located in areas with high proportions of retirees, such as Florida, which has been a longtime retirement magnet. But parts of Appalachia, the Northeast, and the Great Plains are aging not because older adults are moving in, but because so many young adults have moved elsewhere. Over three-fifths of counties in Maine, Montana, Nebraska, North Dakota, and West Virginia have fewer than three working-age adults per older adult. Local areas with sustained outmigration of young adults can experience declining tax revenues, shrinking school enrollments, and declines in the availability of services, such as health care.

This article is excerpted from Mark Mather et al., “What the 2020 Census Will Tell Us About a Changing America,” Population Bulletin 74, no. 1 (2019).


1 Mark Mather, Linda A. Jacobsen, and Kelvin Pollard, “Aging in the United States,” Population Bulletin 70, no. 2 (2015).

2 U.S. Census Bureau, “Population Projections,”

3 Centers for Disease Control and Prevention, “Table 15. Life Expectancy at Birth, at Age 65, and at Age 75, by Sex, Race, and Hispanic Origin: United States, Selected Years 1900–2016” (2017),

4 U.S. Census Bureau, “2017 National Population Projections Tables” (Sept. 6, 2018),

5 Historical sex ratios are derived from Table 5 in Frank Hobbs and Nicole Stoops, Demographic Trends in the 20th Century, Series CENSR-4 (Washington, DC: U.S. Government Printing Office, 2002); and U.S. Census Bureau, 2010 Census Summary file 1; 2017 American Community Survey.

6 Life expectancy represents the average number of years of life remaining at a given age, if age-specific mortality patterns remain constant in the future.

7 Samuel H. Preston and Haidong Wang, “Sex Mortality Differences in the United States: The Role of Cohort Smoking Patterns,” Demography 43, no. 4 (2006): 631-46.

8 Data are derived from Table 5 in Hobbs and Stoops, Demographic Trends in the 20th Century.