In the popular mind, nearly every American city owes its prominence to one private industry or another. The one big city without a defining private industry, of course, is Washington, D.C. The sheer size of the federal government – more than a fifth of the economy – means that a totally hands-off attitude towards industry is impossible. By earmarking resources, changing regulations and imposing tariffs on non-U.S. industries and companies, the thinking goes that it can still foster innovation