The Urbanist Musings of Pete Saunders

Knowing the Difference Between Signal and Noise

Imagine that you are an urbanist in, say, 1951.  

You are a keen observer of urban development trends taking place at the time.  Internationally, the Korean War is ramping up half a world away, but domestically the economy is doing better than it has for many years.  After World War II’s ending in 1945, the American economy went into recession in 1948-49 as businesses reoriented themselves from a wartime to peacetime economy.

This is crucial for your understanding of what’s happening in cities at the time.  Servicemen are coming home again after years abroad, and they’re reestablishing themselves.  They’re going to school, getting jobs, getting married, having kids.  And for the most part, they are building their new lives in cities — yes, cities.  Servicemen returned home to the area most familiar to them and began rebuilding their lives there.  Need evidence of this?  Virtually every major city of the period, mostly in the Northeast or Midwest, reached its population peak in 1950 or 1960, before starting the decades-long decline many would suffer for the next 40-50 years.

As for suburban development, it was a thing.  Development along the periphery was something that had been evident for maybe 50 years prior, but it went through fits and starts, being interrupted by wars and depression.  It was something you witnessed, knew about, but might have believed was inconsequential compared to what was happening in cities at the time.  Its growth certainly paled in comparison to city growth at the time.

At that very moment, 64 years ago, did urbanists view suburban development as an existential threat to cities?  With rare and notable exceptions, the answer is a resounding “no”.  Most, in fact, believed that cities were simply returning to their place in the hierarchy.

We’re at a similar juncture with cities and suburbs today.  Most U.S. cities have been showing signs of stabilization or rebound for the last 25 years.  True, it’s often been minimal when compared with suburban growth, but it does reverse long-time trends.  But now data seems to be coming out that the suburbs are roaring back:

New Census data, though, suggests that eight years after the housing crash, Americans are starting to move back (to the exurbs) again.

The fledgling trend, captured in data through 2014, raises questions about whether American preferences for where and how to live truly changed much during the housing bust, or if we simply put our exurban aspirations on hold. At the same time, the shift calls into question a parallel and popular narrative: that Americans who once preferred the suburbs would now rather move into the city.

The same trend was documented in greater detail at

According to U.S. Census Bureau data released this week, 529,000 Americans ages 25 to 29 moved from cities out to the suburbs in 2014; only 426,000 moved in the other direction. Among younger millennials, those in their early 20s, the trend was even starker: 721,000 moved out of the city, compared with 554,000 who moved in.1 Somewhat more people in both age groups currently live in the suburbs than in the city.

Indeed, for all the talk of the rebirth of American cities, the draw of the suburbs remains powerful. Across all ages, races, incomes and education groups, more Americans are still moving out of cities than in. (Urban populations are still growing, but because of births and immigration, not internal migration.)

I don’t dispute the data.  I’m sure that it’s likely accurate and depicts recent growth and migration activity.  But there are a couple points I would make about it.  First, I think it’s unwise to characterize cities and suburbs as being in competition with each other anymore.  There are urbanists seeking signs of a city triumph over suburbs; there are suburban supporters who would like nothing more than to have suburbs continue their reign over cities.  However, I think it’s more accurate to say that our metro areas are in the early stages of a “Great Congealing” — erasing differences between the two.  I brought this up a year and a half ago:

What I believe will happen is that perceived differences between “city” and “suburb” will begin to disappear. Suburbs will introduce more housing types than conventional single-family homes, to attract a more diverse group of residents. Edge cities will become more walkable. Downtowns and town centers will emerge where currently none exist. They’ll have to respond to the aging of their residents and the needs they have. Similarly, cities will continue to attract young, educated and affluent residents who will be attracted to the inherent adaptability of cities – their transit networks, mix of housing types, job centers, and amenities. 

On the surface, in many places it will appear as the “city” is gaining as the “suburbs” are losing. However, the truth will be that there will be greater economic and social balance between the two, and that both will begin to look more similar than dissimilar. To me, this is a positive. I see this as a trend that will accelerate after 2020.

Second, I’m going to invoke the name of Nate Silver’s recent book, The Signal and the Noise.  There are going to be variations and fluctuations in data — noise — but we must always be mindful of overall patterns — signal.  I think we’ve seen enough stabilization and rebound in cities to believe that it’s here to stay for some time.  I think, conversely, we’ve seen enough movement of typically “urban” challenges — spreading poverty, growing inequality — in suburbs to believe that’s also a long-term trend.  Those trends equal the signal.  Recent data, for three years, on migration patterns immediately after this nation’s deepest economic downturn since the Great Depression might just be noise.

As for the rare and notable exceptions to suburbia that I alluded to above, here’s a quote from Lewis Mumford in his book The City in History:

Under the present dispensation we have sold our urban birthright for a sorry mess of motor cars. As poor a bargain as Esau’s pottage. Future generations will perhaps wonder at our willingness, indeed our eagerness, to sacrifice the education of our children, the care of the ill and aged, the development of the arts, to say nothing of ready access to nature, for the lopsided system of mono-transportation, going through low density areas at sixty miles an hour, but reduced in high density areas to a bare six. But our descendents will perhaps understand our curious willingness to expend billions of dollars to shoot a sacrificial victim into planetary orbit, if they realize that our cities are being destroyed for the same superstitious religious ritual: the worship of speed and empty space. Lacking sufficient municipal budgets to deal adequately with all of life’s requirements that can be concentrated in the city, we have settled for a single function, transportation, or rather for a single part of an adequate transportation system, locomotion by private motor car.

The suburbanization process had been underway for decades before accelerating in the 1950’s.  Mumford wrote the above in 1961.  As I said in 2013, none of what’s happening in cities and suburbs will be clear until after 2020.

2 Responses to “Knowing the Difference Between Signal and Noise”

  1. Alon

    Two things bother me about the \”it's births and foreign immigration\” line:First, immigration is still migration. In fact, since many cities are constrained by the allowed housing supply (hi, New York and San Francisco), every foreign immigrant replaces a domestic net migrant. But even elsewhere: why does it not count that Mexicans, Chinese, Dominicans, etc., are moving to cities more than to suburbs? Why do only the moves made by native-born Americans count?Second, the births angle, and to some extent the division between domestic and international migration, misses the effect of which stages of their lives people move in. Suppose that single people move to the city, get married, and move out when their kids reach school age. The city will constantly register negative net migration, with population growth coming only from natural growth. But this is a trend that can continue permanently, even in a closed system with replacement-level fertility and no net changes in city or non-city population. The comparable issue with international migration is that if immigrants all move to the city but their children all move to the suburbs, this will register as a strong domestic net migration even though the overall effect of this trend on the city's population is zero.


  2. Anon

    One thing Chicago taught me is never use data defined by the city limits as an indicator of any one trend. Virtually all anecdotal evidence/narratives about \”millenials\” and the return to cities are about college grads. Well they only make up ~35% of the population (34% of 25-29 year olds). Gentrification drives an amenity-rich experience: (walkability/bars, restaurants, retail/good schools/high quality of housing stock/crime that's low relative to historical urban standards (though not yet to suburban levels). But for the other two thirds of the population, household income continues to decline in real terms and suburbs can offer a compelling value proposition. Aggregate data isn't necessarily going to fit any single narrative. Experiences are vastly dis-separate across our various sub-cultural groups.Sources:



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