Part 2, Chapter 11, The Need for Concentration Summary and Analysis

Population density is another of Jacobs' success factors. This concentration includes visitors as well as residents. High population densities in residential areas do not necessarily lead to slums. Jacobs discusses neighborhoods in various cities with comparable high population densities and finds that some are successful, such as Greenwich Village and some are not, like Roxbury. Many city slum areas have low population densities as in Oakland, Cleveland, Detroit, and New York. Population densities are not the whole story of diversity.

A high population density is not the same thing as overcrowding. Overcrowding is defined as 1.5 persons per room. Overcrowding can occur in high-density areas or in low-density areas. Densities should be at a level that promotes diversity. Jacobs calls a figure of 100 dwellings an acre the "in-between" densities. How high can...