Not sure why people disagree with this answer. There are clearly creative fields where the top jobs and opportunities are indeed concentrated in a specific set of large cities. Probably more so than most other types of fields. More so than tech, for example, web/social/mobile in Silicon Valley notwithstanding.

That said, other industries are geographically concentrated as well. If you have your heart set on working in the oil business, you probably shouldn't set your sights on living in Boston.