In recent decades, numerous industrial clusters have developed around the world. Some of the best known are the knowledge clusters around Silicon Valley (for information technology), Hollywood (for entertainment), and Boston (for life sciences). In each case, one of the most powerful lures for companies and employees has been knowledge spillover. Strong clusters are ecosystems of venture capital resources, universities, research centers, employers, highly skilled workers and institutions for collaborations, such as chambers of commerce. There are questions, however, about the nature of the economic benefits knowledge clusters are capable of generating. While such clusters can generate employment for highly skilled engineers and scientists, for the most part they do less to directly address the problem of unemployment among less educated and less trained workers.