chspter 11&12:

in chapter 11&12 JACOBS talk about the need of concentration,This concentration includes visitors as well as residents. High ppulation densities in residential areas realy in need for this concentration it is very important for those places and high population density is not the same thing as overcrowding.But Jacobs discusses neighborhoods in cities with comparable high population densities and that some are successful, such as greenwich Village and some are not, like Roxbury. Many city slum areas have low population densities Ex. Oakland, Cleveland, Detroit, and new york. Densities should be at a level that promotes divrsity.