Crabgrass Frontier: The Suburbanization of the United States is a book written by historian Kenneth T. Jackson and published in 1985. Extensively researched and referenced, the book takes into account factors that promoted the suburbanization of the United States, such as the availability of cheap land, construction methods, and transportation, as well as federal subsidies for highways and suburban housing. Introduction Jackson attempts to broadly interpret the American suburban experience, which he views as unique. He states that "the United States has thus far been unique in four important respects that can be summed up in the following sentence: affluent and middle-class Americans live in suburban areas that are far from their work places, in homes that they own, and in the centre of yards that by urban standards elsewhere are enormous. This uniqueness thus involves population density, home-ownership, residential status, and journey-to-work." His working definition of suburbs has four components: function (non-farm residential), class (middle and upper status), separation (a daily journey-to-work), and density (low relative to older sections). Also dominant in the book is the notion that the wealthy began the flight from the city first—something that the middle classes eventually emulated as city tax rates gradually increased to pay for resulting urban problems—as the poorer classes remained in the older central urban areas. Suburbs as substandard From ancient times, the city's primary function was as a central meeting place to conduct business. Jackson argues that before 1815 and the industrial revolution, every major city was a "point" on a map that could be walked from edge to centre in two or three hours. Cities had five characteristics: High population density or "congestion", comparable to New York City in the 1980s: 35,000-75,000 residents per square mile. Sharp distinction between country and city. In Europe the demarcation was a literal wall of defense (nowadays city walls may have been replaced by a ring road or business boulevard). Mixture of functions with neighborhoods: without industrial factories, neighborhoods mixed commercial and residential activities. Short distances between work and residence; most people had to walk to work, and often lived and worked in the same building. Centrality of culture and elite residences. The upper classes lived within walking distance of work and cultural activities, while the poor laborers lived on the periphery of the urban areas along with the undesirable smells of trades like animal skin tanning and soap-making. “Suburbs, then, were