by Ryan Avent Conveniently for me, the fellows at Freakonomics have published a roundtable on the future of the suburbs, which has itself prompted some good commentary. I think there are three things worth emphasizing. The first is that gas prices aren't the only force shaping development, so we shouldn't over-concentrate on that. There are also demographic changes--the population is growing and getting older, family sizes and structures are changing, and so on. There are technological changes--communications technologies will make it more important for some jobs to concentrate together and less important for others to do so, while transit and automobile and energy technologies will influence the shape of future growth. There will be changes in tastes. And the policy environment will also change. Human geography is constantly in flux, and we should not expect development in future decades to look like it did in past decades. Point two is that people will respond to changing economics in multiple ways. When gas prices were low in the late 1990s we saw fuel economies decrease, cities rapidly expand outward, and various other changes. High prices will have the opposite effect. Fuel economy will continue to increase. The outward growth of metropolitan areas is likely to slow, and everywhere within metropolitan areas growth is likely to be denser. Cities will respond to higher demand for alternatives by providing more transit options, improving bike infrastructure, and focusing on walkability. Work weeks may shorten and telecommuting increase. Different people and different firms will act to minimize costs in different ways. Many of these changes can already be observed and indicate what more we might expect, but long-term responses will be more significant than short-term responses. Finally, in making policy, we ought to take a broad view of what can be done to address multiple problems. Shifting funds toward transit, for instance, will do more than provide an alternative means of transportation, allowing folks to reduce their gas expenditures. It also reduces highway congestion and accidents, reduces per capita energy use and carbon emissions, incentivizes denser, walkable growth that reduces energy use and per capita vehicle miles traveled, increases employment opportunities for low-income households, and so on. Suburbs are beginning to see that rezoning to allow density and mixed-uses not only provides experiences consumers enjoy, but also increases tax revenue, encourages walking and reduced energy use, and so on. In other words, transportation policy shouldn't be considered apart from housing policy, energy policy, social policy, and environmental policy. These things are tightly linked, and those linkages should inform our policy decisions. As important as what policy changes are adapted is the need to change how we view policy.