Since the 2010s, the fertility rate of the United States has declined below replacement level, prompting projections of an aging population and workforce, as is already happening elsewhere in the developed world and some developing countries. The decline has been most noticeable since after the Great Recession of the late 2000s. Nevertheless, the rate of aging in the United States remains slower than that seen in many other countries, including some developing ones, giving the nation a significant competitive advantage. Unintentional pregnancies have become less common; in particular, teenage pregnancies have dropped to record lows.

During the 2010s and early 2020s, many Baby Boomers continued to postpone retirement while Millennials and Generation Z were responsible for a surge in the labor force. Still, seniors have been retiring faster than youths can replace them, partly due to the time needed to acquire the necessary skills and knowledge. Going forward in the 2020s, a priority for state legislatures is to retain and attract skilled workers from other states. At the national level, the United States faces shortages of skilled workers, but does not offer foreign talents, including graduates of American universities, a straightforward path towards residency or citizenship.

At the same time, industrial automation has accelerated to address the labor shortage while a combination of population aging and growing public skepticism has led to the shrinkage of higher education. There are currently many high-skilled jobs that do not require a college degree.

Women's workforce participation has grown as the nation's birthrate declines, opening up more opportunities for them. But American women continue to have more children on average than their counterparts in other industrialized nations despite the fact that the United States does not offer generous welfare programs by comparison. Given the experience of other countries, pro-natalist policies such as paid maternity leave are unlikely to significantly increase the birthrate in the United States. As the youth bulge fades away after the 2020s, the United States may be less prone to sociopolitical instability.

While it remains unclear how population aging would affect the United States in the long run, the basic assumptions of economic growth and social welfare programs predicated on population growth would have to be re-examined. However, fears of a demographic cliff may be an overreaction. As economist Claudia Goldin explains, "Scarcity is everywhere; trade-offs are everywhere. There is no optimal birth rate."

History

Aside from the baby boom that followed the Second World War, the birth rate in the United States has declined steadily since the early nineteenth century, when the average person had as many as seven children and infant mortality was high. Americans of all ethnic groups and socioeconomic classes were having fewer children towards the end of the nineteenth century. For example, European-American women living in the North had an average of only three and a half children by 1900.

In a 1905 speech, President Theodore Roosevelt criticized Americans for having fewer children, and described the declining birth rate as a "race suicide" among Americans, quoting eugenicist Edward Alsworth Ross. During the 1930s, the Great Depression caused a substantial decrease in the birth rate, but this trend was reversed by the baby boom that followed World War II, thanks to a combination of economic prosperity, rapid technological progress, and medical advances making housekeeping and child-rearing less onerous for women. In 1960, the total fertility rate of the United States was 3.6. American parents of the postwar era married earlier and had more children than their predecessors. Towards the end of the twentieth century, however, like other Western nations, the United States witnessed a general decline in the desire for children, and the prevalence of childlessness—voluntary and otherwise—increased.

While U.S. fertility rates were roughly at replacement level during the 1990s and early 2000s, they declined during the 2007-2009 Great Recession and, contrary to expectations, never rebounded afterwards even though the U.S. economy had recovered. During the second half of the 2010s, the rate of population growth of the United States was in steady decline. The 2020 Census reveals that the number of Americans aged five or younger is lower than in 2010. Between the mid-2010s and the mid-2020s, all states saw a fall in fertility; states with the highest fertility rates had the steepest decline. Much of this decrease was concentrated in rural counties and in communities with traditionally high religiosity and birth rates, such as Utah. The COVID-19 pandemic further reduced the birth rate, a "bump" in 2021 notwithstanding, while also increasing the death rate in the country. At the same time, many women are choosing to delay childbearing or to forego having children altogether, a trend observed among both married and single women. By 2024, the total fertility rate of the United States fell just under 1.6, the lowest on record. The rate of population growth in the early 2020s was at a historic low, driven mainly by immigration. At current trend, Millennials are on track to have the lowest birth rate in history. Between 1990 and 2015, the number of married couples aged 18 to 34 with children dropped from 37% to 25%. An analysis by the University of New Hampshire showed that 5.7 million more women of "childbearing age" had no children in 2024 compared to the historical trend, up from 2.1 million in 2016. Longitudinal analysis suggests that American women are not merely postponing having children but are increasingly avoiding it altogether. However, among Millennial women who have given birth, the average fertility rate is about 2.02 children per woman.

Regardless, U.S. birth rates have been on the decline across virtually all age groups, socioeconomic classes, and races since the late 2000s. This trend could cause the general population of the country to age significantly in the future. The oldest Baby Boomers, a large demographic cohort, had started to reach retirement age in the 2010s. The median age of the United States rose from 28.1 in 1970 to 39.1 in 2024. An increase in median age is seen among all ethnic groups, though European Americans are currently the oldest by that measure, followed by African Americans and Asian Americans (including Amerindians and Native Alaskans); Hispanic and Latino Americans are the youngest. As of 2023, Maine (median age 44.8) and New Hampshire (43.3) were the oldest states in the Union, while Texas (35.5), the District of Columbia (34.8), and Utah (31.9) are the youngest. The U.S. Census Bureau estimated that at current trend, the number of older adults would outnumber children by 2035. Rural communities are aging the fastest.

In the modern world, it has become common for developed countries to fall below the replacement level of births or see population decline. Many of these countries have tried to launch government initiatives to combat this trend, including large cash incentives for having more children, but these programs have been largely ineffective. Nevertheless, American women tend to have their first children at an earlier age and end up having more children than their counterparts from other developed countries even though the U.S. does not have social welfare programs that are as generous as other rich nations.

Given 2020 demographic trends, it is projected that the U.S. population would grow slightly by 2100, while other countries, including China and India, would shrink. By the end of the twenty-first century, the United States could comprise 4% of the global population, where it is now, and the median age could reach around 45, making the nation younger than China, Japan, and the European Union. However, the number of Americans aged 65 and over will exceed that of children below the age of 18, according the U.S. Census Bureau.

Causes

During the nineteenth century, the Industrial Revolution was under full swing and the United States became an increasingly urban society. As a consequence, fertility rates steadily fell during this period. Women born during the first decade of the twentieth century saw another dip fertility because they came of age during the First World War, the Spanish flu epidemic, and the Great Depression. Today, population aging and falling birth rates in the U.S. are driven by a variety of factors. While economic troubles and climate anxiety are commonly cited reasons, data suggest they are not the primary factors behind falling fertility in the U.S. Rather, it is due to changing attitudes; today's young people, especially women, tend to prioritize and expect more from their careers and are less interested in having children. Access to reliable contraception is another important factor. According to the Pew Research Center, the number of non-parents aged 18 to 49 who do not expect to have any children has grown. Among them, a lack of interest in children, medical issues, and financial problems were the top reasons for their predictions. Those who have children tend to do so later in life and they have fewer of them. Majorities of Americans no longer consider parenthood a source of happiness or fulfillment, and large numbers are not concerned about the nation's falling birth rate. Moreover, from the late twentieth century onward, the United States has become a fairly stable environment with low infant and child mortality rates on one hand and a competitive society on the other. This means that it is preferable for parents to have fewer children and invest more in each. Indeed, parenting in the United States has become increasingly intensive and costly. Middle-class households' spending on childcare has quadrupled between 1995 and 2023.

One outcome of the COVID-19 pandemic, as can be seen from online discussions, is that people have become more willing to openly discuss the difficulties of parenting and to challenge the cultural assumptions about being childfree. As parenthood continues to lose its appeal, more and more Americans prefer their own careers, leisure time, savings, and personal freedom to having children and fewer consider children to be a source of happiness or fulfillment. Among those with children, some have chosen not to have more either because they do not want them, because they would like to spend more time with the ones they already have, or because could not afford more children. In fact, many admit that their financial circumstances would improve once their children leave the house and that they would be better off not having children. Among those having fewer children than they would like, concerns over the state of the economy and personal financial security are common and many believe the cost of raising a child is too high. More and more women are realizing that having children is an option they can ignore in favor of economic or educational opportunities; some worry that a woman's career might stall if she chooses to have children. The number of American women earning university degrees has grown relative to men's since the late 2000s, coinciding with the long-term decline in birth rates. Globally, gender equality is associated with lower fertility. Women with access to contraception, (higher) education, and professional opportunities tend to have fewer children, if at all.