After my recent post on population and population density, a friend of mine tipped me to an interview on planetizen.com and a new study out of Brown University that shows that for every significant highway that gets built through a city, the population of that central city declines by about 18 percent.
Brown economics professor Nathaniel Baum-Snow says highway construction, overall, has been a good thing.
"I do think that there was a welfare benefit from highway construction for a lot of people. People get to live in bigger homes, they have more choice in where they'd like to live. Now most households are dual-worker households, which wasn't true back in 1950. Highways have allowed two people living in the same house to commute to different areas each day."
Though an economist, he wrote his 2000 dissertation on the effect of public projects to expand urban rail transit, and says he always had an interest in public policy. When writing about highways and suburbanization, Baum-Snow realized that there isn't a lot of empirical evidence about how employment centers moved from the central city to the suburbs or how commutes have changed over time.
"Not only has the nature of residential and employment locations have changed dramatically, but the nature of commuting patterns have also changed dramatically. Now, the vast majority of commutes do not involve the central city at all, even commutes made by people who live in metropolitan areas, whereas in 1960, the majority certainly involved central cities either as origins or destinations or both. And that’s a major change," Baum-Snow says.