The Korean previously wrote about ethnic niche businesses -- for example, apparently Koreans are prevalent in the donut stores around Dallas/Ft. Worth area. An interesting New York Times article discusses the same idea in New York:
For generations, sociologists have been studying the way immigrant groups gravitate to such pursuits and professions. In New York lately, Filipinos and West Indians dominate nursing. South Koreans have a lock on fruit stands, delis and nail salons, while Afghans have established themselves as the city’s fried-chicken and coffee-cart kings. In the past, ethnic niches have been so distinctive that speaking of a Jewish social worker or an Irish cop seemed a redundancy. In the late 1970s, a Greek luncheonette that seemed to serve mostly “cheezborger, cheezborger” became a running skit on “Saturday Night Live.”
In a Deadly Bus Crash, an American Tale [New York Times]