For decades, the share of U.S. children living with a single parent has been rising, accompanied by a decline in marriage rates and a rise in births outside of marriage. A new Pew Research Center study of 130 countries and territories shows that the U.S. has the world’s highest rate of children living in single-parent households.

Almost a quarter of U.S. children under the age of 18 live with one parent and no other adults (23%), more than three times the share of children around the world who do so (7%). The study, which analyzed how people’s living arrangements differ by religion, also found that U.S. children from Christian and religiously unaffiliated families are about equally likely to live in this type of arrangement.

In comparison, 3% of children in China, 4% of children in Nigeria and 5% of children in India live in single-parent households. In neighboring Canada, the share is 15%.

While U.S. children are more likely than children elsewhere to live in single-parent households, they’re much less likely to live in extended families. In the U.S., 8% of children live with relatives such as aunts and grandparents, compared with 38% of children globally.

Researchers have different ways of categorizing single-parent households. In this report, single-parent households have a sole adult living with at least one biological, step or foster child under age 18. Some other organizations, including the U.S Census Bureau, also include households that have grandparents, other relatives or cohabiting partners present.

Economic well-being a factor in household size

Around the world, living in extended families is linked with lower levels of economic development: Financial resources stretch further and domestic chores such as childcare are more easily accomplished when shared among several adults living together.

The U.S., like other economically advanced countries, particularly in Europe and northern Asia, has relatively small households overall. The average person in the U.S. lives in a home of 3.4 people – which is less than the global average of 4.9, but slightly higher than the European average of 3.1. In the U.S., Christians (3.4), the unaffiliated (3.2) and Jews (3.0) live with roughly the same number of household members.

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However, household sizes vary by age – the average U.S. child under 18 lives in a household of 4.6 members, while the average adult age 60 or older only lives with one other person.

In early adulthood, Americans continue to live with their parents at relatively high rates. Adult child households account for 20% of Americans between the ages of 18 and 34. (Adult child households are defined as at least one parent living with one son or daughter 18 or older and no minor children or other family members.) Young adults in the U.S. are similar to their Canadian counterparts in this regard, and North America has a higher share of young adults who live in this arrangement than any other region.

U.S. differs in living arrangements for older adults

Americans also differ from others around in the world in their living arrangements after age 60. Older adults in the U.S. are more likely than those around the world to age alone: More than a quarter of Americans ages 60 and older live alone (27%), compared with a global average of 16%. There are only 14 countries with higher shares of older adults living alone, and all are in Europe. They include Lithuania (41%), Denmark (39%) and Hungary (37%).

The most common arrangement for older U.S. adults, however, is to live as a couple without any other children or relatives. Almost half of U.S. adults ages 60 and older live in such households (46%), compared with a global average of 31%. Conversely, older Americans are much less likely to live with a wider circle of relatives. Just 6% of older U.S. adults live in extended-family households, compared with 38% of adults ages 60 and older globally.

Living in smaller households after age 60 is often tied to national rates of economic prosperity and life expectancy. Older adults are more likely to live alone or as couples in countries where an average person can expect to live more than 70 years. In countries where lives are shorter, adults 60 and older tend to live with other family members instead. Life expectancy is often linked to other markers of prosperity within a country, so older adults who can expect to live into their 80s also tend to live in countries where living alone is more affordable.

And in countries where governments provide fewer retirement benefits or other safety nets, families often face greater responsibility to support aging relatives. Cultural norms also play a role, and, in many parts of the world, it is expected that adult children will care for their aging parents.

Despite these many differences, U.S. household patterns are also similar to those in other countries in some ways, and a few of these commonalities are tied to gender.

Women ages 35 to 59 in the U.S., for example, are more likely than men in the same age group to live as single parents (9% vs. 2%), a pattern mirrored in every region and religious group around the world.

And women, on average, are younger than their husbands or male cohabiting partners in every country analyzed. That age gap is 2.2 years in the U.S. and in the rest of the world ranges from 2 years in the Czech Republic to 14.5 years in Gambia. Within the U.S., Jewish partners are closest in age, with only one year between them, while Christians and the unaffiliated have an equal gap (2.2 years).

Coupled with women’s longer life expectancy, this tendency helps explain some of the differences in how older men and women in the U.S. live.

More than half of U.S. men ages 60 and older (55%) live with a partner and no one else, while roughly four-in-ten women (39%) do. And almost a third of women ages 60 and older live alone (32%), while this is true of one-in-five men in the same age group (20%).

Note: See full methodology.