New census data suggests demographic patterns not seen since before the 1920s: big cities growing faster than their suburbs.

Driving the resurgence are young adults, who are delaying careers, marriage and having children amid persistently high unemployment. Burdened with college debt or toiling in temporary, lower-wage positions, they are spurning homeownership in the suburbs for shorter-term, no-strings-attached apartment living, public transit and proximity to potential jobs in larger cities.

While economists tend to believe the city boom is temporary, that is not stopping many city planning agencies and apartment developers from seeking to boost their appeal to the sizable demographic of 18-to-29-year olds. They make up roughly 1 in 6 Americans, and some sociologists are calling them “generation rent.” The planners and developers are betting on young Americans’ continued interest in urban living, sensing that some longer-term changes such as decreased reliance on cars may be afoot…

Primary cities in large metropolitan areas with populations of more than 1 million grew by 1.1 percent last year, compared with 0.9 percent in surrounding suburbs. While the definitions of city and suburb have changed over the decades, it’s the first time that growth of large core cities outpaced that of suburbs since the early 1900s…

In all, city growth in 2011 surpassed or equaled that of suburbs in roughly 33 of the nation’s 51 large metro areas, compared to just five in the last decade.

Note: this is from one year of data, 2010 to 2011, it is hard to know whether this is a big trend or not. The different in population growth was 0.2%, not inconsequential but not exactly a big shift either. We’re not exactly at the end of the suburban era just yet.

Let’s say these numbers hold for a few years. It would be interesting to see how suburbs respond. It would also be helpful to see if the people who are moving to the city are doing so from inner-ring suburbs, exurbs, or somewhere in between as these different types of suburban communities would likely respond in different ways. I could imagine scenarios where built-out larger suburbs, places like Naperville, push for denser and taller developments in order to try to attract residents.