Planners’ Assumptions about Future Household Size and Car Usage May Prove Wrong

Northampton’s Planning Department observes that average household size in the city has fallen from 2.86 in 1980 to 2.14 in 2007. They believe this trend will continue:

Average household size (people per dwelling unit) will continue to decline. This will be driven by decreases in average family size, the number of children and number of “traditional” families, and a corresponding increase in the number of child-free families, child-delayed families, and especially empty nesters and senior and frail elderly populations.

(Northampton Schools Strategic Planning: Demographic Background and Sustainable Northampton, 2008, PDF, 803KB)

What if, however, much of the past trend was driven by the enormous debt-fueled consumption bubble that dates back to the 1980s? There are signs that this trend has stalled or is even unwinding. For example, today’s Wall Street Journal reports:

Homeward Rebound: Weathering the Storm With Kin

…Families around the country are weathering out the recession by hunkering down with relatives and friends. It’s not just a lower-income phenomena either. The homeward bound are former white-collar and blue-collar workers who believe they might have a better chance finding work in their hometown because they know more people, who, in turn, know still more people. But with jobs scarce, that doesn’t always work, and rumors of jobs are just that. At home, though, they can at least get help with food, shelter and clothing.

“As Americans face tougher economic conditions, we’ll likely see more of this,” said Jim Toedtman, a vice president with AARP, which analyzed Census data. More adult children are living with their parents — about 6.2 million in March 2008, the latest figures available — up from 6.1 million the year before, continuing a gradual upward trend from 2000. The latest number doesn’t include the most recent and most intense series of layoffs from the last three months, and is likely to be significantly higher now, says Mr. Toedtman…

Kin is becoming the safety net of last resort in part because overwhelmed social-service agencies are reaching their giving limits.

Another common assumption among smart-growth advocates is that cars have proliferated due to government subsidies, advertising, and skulduggery on the part of auto companies. These may be factors, but private cars have real benefits:

The allure of the automobile is compelling, and crafting a sensible transportation policy requires an acknowledgement of the wonderful attributes of the car:

The motor vehicle has enriched our lives in countless ways. It has provided the easy connectivity that enables modern, highly interdependent, urban societies to thrive. It has eliminated rural isolation. It has enabled workers to choose employers rather than accept whatever employment opportunities are within walking or transit distance of their homes. The personal truck allowed craftspeople and artisans to carry their tools with them and enter the middle class by becoming independent contractors. The motor vehicle has enabled people to live outside urban centers and still participate in mainstream society.

The car is an amazing piece of technology that has greatly extended our range of choice as to where to live, work, shop, and play. No other form of transport can compete with the automobile in terms of door-to-door mobility, freedom to time one’s arrivals and exits, protection from inclement weather, and comfort, security, and privacy while in transit.[2]

(Remarks of Emory Bundy, prepared for a conference entitled, “Sprawl and Congestion—is Light Rail and Transit-Oriented Development the Answer?”, 6/17/99)

While most of today’s cars damage the environment and consume fossil fuels, prying people away from them might not be so easy. A plausible future is one where the cars remain but their technology is changed to make them more benign. As we’ve written before, this future may not be so far off:

New York Times: “Electric Cars for All! (No, Really This Time)”

Energy-Efficient Personal Vehicles of the Near Future

Will households grow appreciably in size over the next 20 years? Will the number of cars per capita stay the same? NSNA can’t say for sure, but neither can planners. Sustainable Northampton should be implemented in a way that stays flexible in the face of this uncertainty. Otherwise, there’s a risk of making Northampton’s “receiving areas” too dense, leading to serious traffic and parking problems.

See also:

USA Today: “Increase in household size could slow economic recovery”  (5/7/10)
The number of people living under one roof is growing for the first time in more than a century, a fallout of the recession that could reduce demand for housing and slow the recovery.

The Census Bureau had projected the average household size would continue to fall to 2.53 this year. Instead, the average is likely to hit 2.63, a small but significant increase because it is a turnabout…

The USA could end this decade with up to 4 million excess housing units because of the reverse in household size, [says Arthur C. Nelson, director of the Metropolitan Research Center at the University of Utah]….

Multi-generational households are on the rise: 49 million, or 16% of the population, live in a home that had at least two adult generations in 2008. In 1980, there were 28 million, or 12%.

Proposed Future Land Use Map (PDF)

The orange zones are “Traditional Neighborhood and Receiving Areas”. The light green zones are “Conservation Development and Sending Areas”.

Gazette: “Recession even has adult children calling for mommy” (4/27/09)
“In some ways, we’re coming back and living together the way we did during the Depression,” said Amy Goyer, family relationship expert and senior vice president of outreach at, an online community for grandparents.

According to 2008 Census figures, 20 million people ages 18 to 34 live at home with their parents – 30 percent of that age group. Researchers for the Network on Transitions to Adulthood, a group financed by the John D. and Catherine T. MacArthur Foundation, found that since the 1970s, the number of twentysomethings living with their parents has increased by 50 percent. Of those who moved out of the house by age 22, 16 percent returned home before they hit 35, the researchers found.

Recession will probably accelerate the growth of the phenomenon, as many college graduates find themselves in a market where jobs are not available or don’t pay as well as they expected when they took out expensive student loans. Almost half of June 2008’s college graduates had planned to move home after graduation, according to a survey by the employment Web site

Halle-Neustadt: A Case Study in Compact, Transit-Oriented Development
I first became aware of Halle-Neustadt at a 1998 conference on sustainable transportation at which two planners from the University of Stockholm declared it to be one of the most sustainable (i.e., least “auto-dependent”) cities in the developed world…

What the Swedish researchers failed to note in their 1998 presentation, but faithfully recorded in their full paper, was that Halle-Neustadt was only “sustainable” during the socialist period. When Germany reunified, many residents moved out, and those who stayed bought cars so that auto ownership “reached nearly the level of western Germany.” Naturally, this created major congestion and parking problems: “The cars are parked everywhere — on pavements, bike-ways, yards and lawn.”

Berkeley, California: Cautions on Infill
Renters and other high-density residents are expected to do without adequate living space, greenspace, quiet, and cars; and without cars, they lack the freedom, pleasure, and mobility taken for granted by average Americans. This is ethically unacceptable…

NY Times Magazine: “The Autonomist Manifesto (Or, How I Learned to Stop Worrying and Love the Road)”
Smart-growth advocates say that suburbs have flourished at the expense of cities because of government policies promoting cheap gasoline, Interstate highways and new-home construction. What if the government, instead of devastating urban neighborhoods by running expressways through them, instead lavished money on mass transit and imposed high gasoline taxes to discourage driving?

As it happens, that experiment has already been conducted in Europe with surprisingly little effect. To American tourists who ride the subways in the carefully preserved old cities, the policies seem to have worked. But it turns out that the people who live there aren’t so different from Americans. Even with $5-per-gallon gasoline, the number of cars per capita in Europe has been growing faster than in America in recent decades, while the percentage of commuters using mass transit has been falling. As the suburbs expand, Europe’s cities have been losing people, too. Paris is a great place to visit, but in the past half-century it has lost one-quarter of its population…

Intellectuals’ distaste for the car and suburbia, and their fondness for rail travel and cities, are an odd inverse of the old aristocratic attitudes. The suburbs were quite fashionable when only the upper classes could afford to live there…

Some…especially the young and the childless, are moving back to cities, and once again there are private developers ready to meet their desires, which now run toward lofts and historic town houses with modern kitchens. But for most middle-class families, the ideal of city life conflicts with the reality of their own lives. Even if they’re willing to do without a yard, how can they afford to live in a decent neighborhood within easy commute of their jobs? How will they go shopping on a rainy day with a child in tow?

Seeing Like a State: Planning Gone Awry in the 20th Century
“…[T]here is little doubt that [Jane Jacobs] has put her finger on the central flaws of hubris in high-modernist urban planning. The first flaw is the presumption that planners can safely make most of the predictions about the future that their schemes require…”

Scott proposes guidelines to reduce the potential harm from plans. These include:

Take small steps. In an experimental approach to social change, presume that we cannot know the consequences of our interventions in advance. Given this postulate of ignorance, prefer wherever possible to take a small step, stand back, observe, and then plan the next small move…

Favor reversibility. Prefer interventions that can easily be undone if they turn out to be mistakes. Irreversible interventions have irreversible consequences. Interventions into ecosystems require particular care in this respect, given our great ignorance about how they interact…

Plan on surprises. Choose plans that allow the largest accommodation to the unforeseen… In planning housing, it would mean “designing in” flexibility for accommodating changes in family structures or living styles…

Plan on human inventiveness. Always plan under the assumption that those who become involved in the project later will have or will develop the experience and insight to improve on the design… (p.345)