The physical shape of a city is closely tied to the structure of its economy. A city built on shipping is built on water. University towns grow up wrapped around those institutions. In manufacturing metros, the roads lead people to factory hubs, with their bedroom communities nearby.
This relationship between the design of cities and their job centers presents a quandary, though, when economies shift over time. What happens, for instance, when workers move to the fringe of cities to follow manufacturing work, only to find that tomorrow's knowledge-economy jobs have returned downtown? This is a particular problem for transit networks that often have a hard time keeping up with the shifting geography of job opportunity.
But it's also a fundamental challenge for any city where 21st century economies are leaving behind people with the kinds of skills, living in the kinds of communities, that were better suited to a different era. This is happening in many places, but a recent report out of Australia from the Grattan Institute illustrates in precise detail what the mismatch looks like there. Data on housing, income and travel patterns in Australia's four largest cities reveal what authors Jane-Frances Kelly and Peter Mares call "strains in the triangle of work, home and transport that could threaten national prosperity." As they write:
For the economy to function efficiently, these three things need to be in tune. In the 20th century, the outward spread of residential neighbourhoods was compatible with the dispersion of manufacturing into suburban locations, since the rise of the car increased mobility and efficiently connected workers and jobs.
In the 21st century, however, the established structure of our cities and their transport systems is less well suited to the needs of the economy. This is not just a shift from manufacturing to services. More significant is a rising level of knowledge-intensive activity in all sectors of the economy, which increases the importance of efficiently connecting firms, jobs and residents.
In the United States, many knowledge-economy jobs are clustering outside of cities, in places like Silicon Valley and Redmond, Washington. In Australia, though, the vast majority of such jobs are now located in the urban core, where they're now out of reach to many people (given both education and location). This map from the report shows the distribution of median income among working-age adults in the Sydney metropolitan area, with the urban core at right:
Similarly, here is the distribution of adults, aged 25-65, with a college degree:
And here is a picture of how accessible the region's jobs are within a 45-minute car commute:
And a 60-minute transit ride:
Vast stretches of the region have access to less than 10 percent of the area's employment within a reasonable commute.
"For us," Kelly writes in an email, "the important thing for access to opportunity is the coincidence between lower income and lower qualification households and that poorer access to jobs."
This means that workers who once thrived in a manufacturing economy now face twin obstacles: They may not have the qualifications for jobs in the knowledge economy, and they also live nowhere near them.
The report has produced similarly striking supplemental maps for Melbourne, Brisbane and Perth. And no doubt similar pictures could be drawn of any number of American cities.