Over the past three decades, education has become a great divider. Even as communities desegregated racially, they became more segregated scholastically. Urban regions with many college graduates, like Boston or San Francisco, have become "brain hubs." They offer higher wages and longer life expectancy.
At the other extreme are traditional manufacturing centers such as Flint, Mich. In between, according to University of California, Berkeley economist Enrico Moretti, cities could flip either way.
This sounds blindingly obvious. Yet the winnowing has profound implications for today's gnawing debate about why inequality has reached a level not seen since before the Great Depression.
Not everyone can create video games or discover breakthrough medications, of course. Only 10 percent of U.S. jobs are in the innovation sector, Moretti says. Yet the presence of these workers creates demand for local services, which provide the vast majority of today's jobs. Everyone in town winds up earning more than they would elsewhere.
To get a Silicon Valley cooking, you need an intellectual star like William Shockley to draw a bunch of "hot minds" to your startup in the orchards. One thing leads to another, and California ends up producing more patents than any other state.
So how can we boost the number of innovation workers in America and, by extension, create more jobs for everyone else? The answer should be clear: import them or grow our own. Giving work visas to more foreign engineers and scientists would be a cheap solution. Educating more Americans would be costly, yet good for the nation's future, assuming students can be persuaded to major in computer science, chemical engineering and microbiology.
Why not do both?