Seattle is famously a city of booms and busts, going all the way back to our first boom, the Klondike Gold Rush. But over the past 100 years, one thing remained constant: The suburbs of King County grew at a faster rate than the city of Seattle.

Now, with the release of data from the 2020 census, the suburbs’ long run is officially over.

From 2010 to 2020, Seattle’s population grew by an incredible 21%, outpacing the 16% growth of surrounding King County.

It’s quite a turnaround.

Census data shows that starting in 1910, decade by decade, the population growth of the surrounding county exceeded that of the city. Even when the city was booming, like it did in the postwar period, the county boomed more. And when the city’s population was stagnant, like it was during the Great Depression, or shrinking, as it did during the Boeing Bust of the 1970s, the suburbs still registered impressive double-digit growth.

But the 2010s, which has been called the “Decade of the City,” was different. Both millennials and empty-nesters flocked to urban areas, drawn by the appeal of walkable neighborhoods and urban living. Seattle could be the poster child for this trend, with the blossoming (and gentrification) of many of its urban neighborhoods.

Contributing to the city’s revival was explosive job growth in this period, led by Amazon, which moved its headquarters to downtown’s South Lake Union neighborhood in 2010.

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Over the course of the decade, Seattle’s population grew by nearly 130,000, hitting 737,000. The 21% growth rate marks the city’s fastest decade of growth since the 1940s, when the population increased by 27% — and it should be noted that some of the growth in the 1940s was due to the city annexing areas that are now part of North Seattle. None of the 2010s population growth came via annexation.

To be sure, for surrounding King County, the 2010s were still a period of growth. Its 16% population increase exceeded the 13% growth of the previous decade. In the 2010s, the King County suburbs gained about 210,000 residents, hitting roughly 1.5 million.

That said, when you compare the 2010s with the suburban growth rates of the 20th century, it’s clear that things have slowed down dramatically. For example, in the 1960s, King County outside of Seattle grew by more than 60%, and in the 1940s, the population nearly doubled.

Some areas of the county grew a lot faster than others in the 2010s. I divided suburban King County into seven areas so we could see the various patterns of growth across the county, and compare them with Seattle.

Interestingly, none of these seven areas grew as fast as Seattle in the 2010s.

The fastest suburban growth happened on the Eastside, where the population increased by 112,000, or about 18%. The Snoqualmie Valley, which is the sparsely populated and more rural area to the east, grew nearly as fast, at 16%. The slowest growth was on Vashon Island, at just 4%.

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Policy likely plays a role in the slower rates of growth in the suburbs in recent decades. The Growth Management Act, which was adopted by the state Legislature in 1990, regulates development in order to curtail urban sprawl and protect environmentally sensitive lands in fast-growing areas. And since the act went into effect, a greater share of new residential building permits are for development in the county’s larger cities rather than in rural areas.

Census data clearly shows that since the 1990s, the overall growth of the suburban areas of King County has slowed significantly.

Of course, we’re in a new decade now, one that sadly has been defined by the coronavirus pandemic. In particular, it hasn’t been good for cities. In Seattle and other major U.S. cities, downtowns are looking a little rough these days, with boarded-up storefronts and mostly empty sidewalks. There has been a marked increase in homelessness, and homicide rates have increased.

There are already some indications that the trend of the 2010s has turned around, with faster growth in the suburbs than in Seattle. The rise of remote work has made it much easier to live far away from urban job centers.

At this point, it’s probably too soon to say how many of the changes brought on by the pandemic will be permanent, or if Seattle and other cities can rebound.