A large proportion of the world's workers live in communities on the outskirts of cities, what for the want of a better word we might call suburbs. In different places, such communities take different forms. Working-class districts composed of dense, high-rise dwellings ring many European cities, like Paris and Moscow. By contrast, in the United States, Canada, and Australia, working-class suburbanization has been characterized by single-family homes, low density, and automobile dependency. In Latin America, Turkey, and parts of Africa, sprawling self-built communities of shacks and shanties surround major urban centers (a phenomenon that occurred in some North American cities during the early twentieth century).