The first big data release from the 2020 census in August contained some positive news about America’s biggest cities. The biggest of them, New York, turned out to have hundreds of thousands more people than the annual population estimates made by the Census Bureau had projected. Not one of the country’s 10 largest cities lost population between 2010 and 2020, the first time that’s happened since the 1940s. All of them now have more than a million residents for the first time ever.

The top-10’s share of the U.S. population did shrink, as it has with every census since 1930. But the decline — to 7.87% in 2020 from 7.94% of the population in 2010 — was the smallest since then.

Attaching meaning to this statistic is a little complicated. Big-city borders are arbitrary, with some encompassing vast areas, including what most of us would describe as suburbia, and others much more constricted. Four of the 10 biggest U.S. metropolitan areas (Washington, Miami, Atlanta and Boston) aren’t represented in the top 10 cities list. City borders can also change over time, although the biggest such changes affecting top-10 cities occurred long, long ago with the consolidations of Philadelphia in 1854 (the “other urban places” in the chart headline refers to the formerly unincorporated Philadelphia suburbs of Northern Liberties, Southwark and Spring Garden, which all ranked among the 10 largest one or more times from 1800 to 1850) and New York in 1898 (Brooklyn had been the country’s fourth-largest city in 1890). Membership in the top 10 can change as well; one key reason why the downward trend in the above chart flattened out in recent decades is that perennial population losers Baltimore, Cleveland, Detroit and St. Louis fell off the list.

The Census Bureau also divides the U.S. into urban and rural areas, with the urban share of the nation’s population increasing steadily over time, to 80.7% as of 2010 (the 2020 numbers aren’t out yet). But its definition of urban casts an awfully wide net, including every settlement of 2,500 people or more, and is subject to change from time to time (the 2,500 is about to be upped to 10,000, for example).

All of which is a long way of saying that while the population of the 10 largest cities is a flawed measure of urbanization in the U.S., all the other measures are flawed too — and the top-10-city total, available all the way back to 1790, conveys some useful pieces of information. One is that, as already mentioned, the 2010s were not a decade of urban decline. The 10 biggest cities added 1.6 million residents, the third biggest such gain since 1930.

This wasn’t about growing cities replacing shrinking ones on the list: apart from Phoenix and Philadelphia swapping places (to fifth and sixth, respectively, in 2020), the top 10 remained unchanged.

The era of big-city decline that began in the 1930s and really took off as the U.S. suburbanized after 1950 thus seems to have pretty definitively ended. Again, this is partly due to the rise of the sprawling new-style cities of the Sun Belt, but lots of older cities returned to growth as well.

Still, that long era of decline left its mark. The 10 biggest U.S. cities, while large and growing, now account for less than 7.9% of the country’s population.

The modern U.S. is thus a decentralized nation, where despite an urban revival in recent years the periphery has kept growing faster than the center.

The great dispersal brought on by the pandemic and the subsequent turn to remote work threatens this status quo — and it isn’t really reflected in the census data, which is supposed to count people in their permanent place of residence only as of April 2020, which was about when the pandemic really got rolling. Even if these developments don’t spell doom for big cities, they pose challenges. Then again, big U.S. cities have faced some awfully big challenges over the past century, and they’re still standing.

Justin Fox is a Bloomberg Opinion columnist covering business.