Here's another take on it... In the USA, "ethnic" is what food is before it is assimilated into the common experience of most Americans. Indiagirl's point about "ethnic" food being food that requires ingredients that you can't get through mass marketing distribution chains backs up this theory. The cultural and racial aspects are, I'd suggest, artifacts of the distribution networks for the required ingredients. "Ethnic" is a stage that food passes through in the marketplace, until it is either accepted and folded into the mainstream, or remains sidelined for lack of economic pressure to incoprorate it into the mass market. As Indiagirl said, a hallmark of "ethnic" food is that certain ingredients must be imported or otherwise recreated in this country. Who is going to know how to select/reproduce the desired ingredient? Somebody who is from the point of origin, with first-hand knowledge of what the ingredient is like in its original environment. The person with this first-hand knowledge is also likely to have a social network of people of similar familiarity with the foreign point of origin and its language and culture, some of whom are likely to be people who want cook with familiar ingredients in a foreign land, and others are the entrepreneurial budding "ethnic" restauranteurs. Thus is explained the cultural homogenaeity at the beginning of the introduction of food into America. A few examples to beat the dead horse that it is access to non-mainstream ingredients that is a hallmark of "ethnic" cuisine: French isn't "ethnic" because you can walk into a supermarket and pick up just about everything you need to cook a french meal, because those ingredients are in the mass market distribution chain (with notable annoying exceptions like unsmoked bacon.) Southern Italian might have once been "ethnic" when mainstream grocers didn't carry basil and olive oil, though northern Italian would never have ethnic since it's distinctive ingredients (except maybe certain cheeses) have been available in the mainstream larder. Food stops being ethnic when its ingredients reach a critical mass of distribution, and become integrated into the greater melange that American cuisine has become. There was a time, if i recall correctly, that brocolli was considered ethnic italian food. Not any more. Plenty more examples... grocery store pierogies... grocery store dolmas (though very infrequently the grape leaves from which they're made.) Foods transition through "ethnic" status...