http://www.brookings.edu/research/opinions/2015/04/08-detroit-silicon-valley-katz?utm_campaign=Brookings+Brief&utm_source=hs_email&utm_medium=email&utm_content=16987584&_hsenc=p2ANqtz-8Nmq9srHuH8Hya2yJUQ1i3YwrJ2aUkGee2oGyNsB1_ZKpq9rm28win2heoNeuII-M0jSHhgF6GdT0GB5xBvMXFrJEgew&_hsmi=16987584