Thanksgiving is a time when families come together and reflect. So I thought I’d take this holiday as an opportunity to reflect on what census data tells us about Seattle’s families. And this may not comes as a surprise, but Seattle families are anything but average. A few of these stats may surprise you.

Unlike most of America, and even most big cities, families made up the minority of households in Seattle in 2021, the most recent data. There were about 155,000 families in the city, representing 44% of the city’s nearly 352,000 households. Among the 50 largest U.S. cities, Seattle was one of only 12 where families made up less than half of households.

The reason for that is, of course, that Seattle has a lot of single folks. People living alone numbered 141,000, or 40% of all city households — that’s among the highest percentage of any big city.

The Census Bureau defines a family as a household in which at least two people are related by blood or marriage. Besides people who live alone, other households that wouldn’t be considered families in census data include unrelated roommates and unmarried couples, unless they have a child or other related person in the household.

Another way in which Seattle families stand out is their size: They’re small. In fact, among the 50 largest U.S. cities, we had the smallest average family size, at just 2.75 people, and this is a figure that has declined. It was 2.94 in 2010. At the opposite end of the spectrum, Fresno, California, has a 2021 average family size of 3.7 people.

Even as Seattle’s population ballooned in the 2010s, the under-18 population flatlined at roughly 100,000. One reason for the relatively small number of children is that we have a lot of young adults who are less likely to have kids. Seattle was a magnet for millennials in the previous decade, and nearly a quarter-million Seattle residents were between the ages of 20 and 34 in 2021. It is now more common for a woman in King County to have her first child in her 30s or 40s than in her teens or 20s.


Of course, the high cost of living is another factor. Even without children, it’s expensive to live in Seattle. For many couples, the only way to afford children is to move out of the city.

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Most of Seattle’s family households do not include children under 18. There are 82,000 married couples in the city who either don’t have children, or whose children are 18 or older. Another 13,000 city households included some configuration of related people, but no kids under 18. Those two groups account for 61% of Seattle’s families.

That leaves only 60,000 Seattle families with children under 18, and the data shows these households are also far from typical when compared with other cities.

The nuclear family may be on the decline in much of the nation, but it’s alive and well in Seattle. Of the nearly 60,000 families with kids, 44,000 (or 74%) are headed by married couples. That’s the highest percentage of any large U.S. city. It’s also much higher than the national average of 60%.

It’s a sign of our city’s highly educated and affluent population. Research shows that family structures are strongly tied to economic and class standing. Higher-income, well-educated couples are more likely to marry, and to stay married. And poverty rates are higher for households with a single parent, or two unmarried parents.

Just how affluent are married couples with kids in Seattle? The median income for these households was an eye-popping $237,300 in 2021.


Not coincidentally, then, Seattle also had the second-lowest percentage of single-parent households of any large city. Just 17% of households with children were headed by a single parent. The only big city with a lower percentage was San Jose, at 13%.

There were about 7,300 single-mother households and 2,500 single-father households in Seattle. There were also 2,600 unmarried couples with kids. Another 3,100 households included a child being raised by a guardian other than a parent, such as a grandparent.

The median income for a Seattle single mother was a far cry from that of the city’s married couples with kids, at just $58,600 in 2021.