A whopping quarter of American 40-year-olds have never been married—an all-time high, according to a recent Pew Research Center report.

It’s not as if the unwed are cohabitating instead. A mere 22% are living with a romantic partner, according to the center’s analysis of 2022 Census Bureau data, released last week.

The trend of never-been-married mid-aged Americans has been decades in the making. For the first decade of the 20th century, only around 16% of 40-year-olds had never married. That rate began dropping shortly thereafter and fell dramatically during the postwar years—to a low of around 6% in the 1960s, 1970s, and 1980s. But in 2010 the rate of unmarried 40-year-olds then began a dramatic upward ascent to 20%, and up another 5% to 25% in 2021, according to Pew.

That a record number of the country’s 40-year-olds aren’t married—and that most unmarried 40-year-olds aren’t cohabitating—signifies shifting norms in family formations.

Millennials—the 40-year-olds in question—have historically been less enthusiastic about marriage and childbearing than their parents, or have at least delayed the milestones while they prioritize their careers and their finances. Two recessions before midlife, a subpar job market postgraduation, massive student loan debt, and a housing affordability crisis certainly haven’t helped matters.

Waiting until later in life to form a family, or merely choosing singledom, is one factor of many affecting the country’s fertility rate, which has been on the decline for several decades. It never rebounded after the Great Recession and hit a record low in 2020, according to a recent report from Pew Charitable Trusts.

But some 40-year-olds were more likely to have never married than their peers, Pew’s analysis found. That includes men compared to women; Black Americans compared to Hispanics, whites, and Asians; and nondegree holders compared to those who graduated from college.

The largest percent of unmarried 40-year-olds held only a high school diploma or less (33%). A little over a quarter held an associate’s degree or had attended some college, but hadn’t graduated. Less than a fifth held a bachelor’s degree or higher.

Wedding bells should still be in the future for about a quarter of unmarried 40-year-olds if historical trends hold, Pew’s Richard Fry, a senior researcher with the organization, noted in a recent blog entry.

But a rising percentage of Americans are forgoing marriage—and cohabitation, too, according to a 2021 Pew analysis of Census data. In 2019, roughly 40% of adults ages 25 to 54 were neither married nor living with a partner—up from 29% in 1990.

It’s a statistic with potentially significant economic implications. Unmarried adults typically earn less than partnered adults, are more likely to be unemployed, are less likely to attain educational milestones, and fare worse when it comes to health outcomes.