Indeed, increasingly now, many people have multiple national identities and even dual citizenship, they appreciate multicultural experiences, and they value diversity of opinion and experience as a source of social capital.

In other times and places, as in cosmopolitan cities, the boundaries between many ethnic groups may be vague and the realms of life governed by ethnic designation more limited.

This was the case in the Southern United States during the years of the Jim Crow laws and in South Africa during the years of apartheid.
In both cases racial groups were legally segregated.

Sometimes boundaries between ethnic groups, for example, may be sharp and sustained by law and custom that restricts communication and movement across ethnic borders.

A relatively benign example can be found in the context of sporting events, where the hometown fans may celebrate the qualities and virtues of their team while chastising the qualities of the visiting team or taunt and disparage the character of a particularly disliked star on the opposing team.