Hirt does four things in this volume. First, she lays out the essentials of American zoning and planning without getting lost in the details. Second, she makes the comparative case for the uniqueness of the United States in terms of its degree of spatial homogeneity and protection of the idealized single-family, detached house. Third, she gives a quick tour of the history of spatial separation in cities and especially the rise of urban planning in Europe, before returning to the deep roots of "exclusive domesticity" in America ideology from the colonial era onward. Finally, she provides a fine, brief history of the establishment of deed covenants and municipal zoning in the US case.
The essence of Hirt's analysis is that American zoning is distinct from all other national planning practices, and that it is so because the spatial order of American society and cities is unique. In this, history matters in showing the depth of American ideas and permanence of US practices concerning what Hirt calls "spatial individualism": freedom conceived geographically as isolation and elbow room. Frederick Jackson Turner goes to town, as it were. Along with this came a uniquely American preference for the single-family, detached house, which dominates urban space and legal practice as in no other country. Hirt certainly recognizes the importance of separating noxious uses from domestic tranquility as the foundation for zoning, but she is nicely attuned to two other things vital to spatial freedom in the American sense: freedom from having to mingle with the lower classes and races and freedom to profit from property development by keeping government at bay except to minimize uncertainty and risk. The desire for spacious, single-family housing segregated by class, race, and function was deeply ingrained in popular bourgeois culture.
One thing I particularly like in Hirt's historical approach is that, unlike almost all other treatments of zoning and spatial segregation in American cities, this one does not begin after World War Two and does not put the bulk of the blame on the federal government's mortgage policies. The New Deal simply put federal muscle and money behind what was already standard practice locked into the fabric of urbanization by the real estate industry and Herbert Hoover in the 1920s. As is so often the case in the United States, government policy and business interests went forth hand in hand to build cities profitably.