Much of the received wisdom in planning circles is that migration out of the urban core is a primary driver of suburban population growth. In fact, most suburbs owe their growth to migration from rural areas and small towns, not central city residents escaping the urban core.
"There are, of course, significant individual exceptions. Virtually all of the first world core cities that have achieved a population of more than 400,000 – if they have not expanded their boundaries and did not have substantial empty land for development – experienced losses to 2000. Yet even in most of these cases, the majority of suburban growth was from outside the metropolitan areas, rather than from the core cities. For example:
- St. Louis is a champion among the ranks of population losers, having lost the greatest percentage of its population of any large municipality in the world, (dropping from nearly 860,000 in 1950 to 350,000 in 2000). Indeed, it may be fair to say that St. Louis has lost more of its population than any city since the Romans sacked Carthage. Yet, even in St. Louis, 60 percent of suburban growth was from outside the metropolitan area, rather than from the city.
- Few core cities have lost the nearly 1,000,000 residents that have fled Detroit since 1950. Yet, even in Detroit, 65 percent of suburban growth was from outside the metropolitan area, rather than from the city.
- The city of Chicago lost 725,000 residents between 1950 and 2000, yet 82 percent of the suburban growth was from outside the metropolitan area.
Wendell discusses a number of world cities as well, including Paris and Tokyo, to make his piont.
The implications are important for understanding travel, as Adrian Moore and I discuss in our book Mobility First. As jobs decentralize to non-central city core areas, the idea of the hub and spoke approach to organizing the road network (with a central city as a hub). The new jobs are really growing up in new kinds of urban places with links and destinations separate from the urban core.
With this type of growth pattern, point-to-point trips are more numerous and more reflecting of complext metropolitan area travel patterns. In short, we need to think of a spiderweb, not a wagon wheel (Chapter 3 in our book).