There are a number of small towns, villages communities and neighborhoods around the US which are pretty much available for groups of only a certain background or way of life. There are shtetls like New Square or Kiryas Joel, all sorts of Amish settlements, ecovillages, Indian reservations, all sorts of communes based on different ideals (religious, political, sociological) and other types of intentional communities. These all discriminate when determining membership, although I'm also sure there is little pull for outsiders to join such communities in the first place.
Russian defense ministry: Plane sent to intercept U.S. plane near border on Friday (Reuters)
from the article: Can't we all just get along - separately?