“New Visions for Metropolitan America” begins with a succinct, if familiar, critique of low density urban development in post-war America. However it quickly reveals itself to be a manifesto for a ‘new’ planning approach that addresses the sociological and economic malaise attributable (in the author’s view) to suburban sprawl. It is a book aimed at policy makers rather than planning theorists, and written with the appropriate degree of zeal.
In his opening preamble the author identifies five American aspirations that underlie the rationale of low density development. These are: (1) an overwhelming desire for detached, single-family homes; (2) heavy reliance on private automobiles; (3) the proliferation of low-density, landscaped workplaces scattered throughout the suburbs; (4) preference for small-scale government; and (5) a trickle-down approach to housing the poor.
Downs argues that these aspirations have eroded the traditional view of urban life as center-focused, and have instead led to a view of urban societies as ‘low density networks’: “Facilities once found only in or near the center were replicated in outlying locations…More and more residents not only lived far from the initial center, but worked, shopped, and did everything else far from it too.”  As the outlying networks develop, “its original center becomes harder to reach from its extremities, and movements flow more and more from one point to another around the area’s periphery, without reference to its original center…Intensification reduces the dependence of the outer edges on the original center, so that the center becomes weaker both relatively (which has happened in all U.S. metropolitan areas) and eventually absolutely (which has not yet happened in most of them).” 
Here, as elsewhere in the book, Downs betrays an Elysian view of the urban past in which cities once had proper centers patronized by mixed-income city dwellers living and working close by in high density neighborhoods – the physical and functional boundaries between city, suburbs and country were clear and the various parts existed according to an efficiently executed planning rationale. In essence this is a description of ‘downtown’, an urban construct that is exclusively American. Whether or not ‘downtown’ has ever been more than a utopian ideal is open to debate. It does not however underlie the European model of growth which is far more akin to the low density network model that Downs dislikes, with outlying villages enlarged and absorbed into the growing metropolis. In the case of London the center (or City) ceased to be the metropolitan focus many centuries ago, and Londoners now view their individual boroughs or neighborhoods with its retail and commercial facilities as their particular urban focus.
The author is on stronger ground in concluding that American ‘nimbyism’ is a significant factor in the decline of U.S. metropolitan areas. The absence of regional or metropolitan planning authorities results in a Darwinian competition of survival between adjacent urban districts. In the Bay Area of San Francisco, for example, there is almost no redistributive funding or cross-subsidy arrangements. Wealthy conurbations, such as Berkeley, contributes very little to its poorer neighbors Oakland, Richmond and San Pablo in spite of their greater social welfare, policing, and housing demands. This creates a pattern of neighborhoods in extremis, some wealthy, some very poor, or stratified along ethnic or cultural lines. Downs highlights how this stratification is perpetuated by individual city authorities through the adoption of zoning ordinances, building codes, subdivision restrictions and other regulations that serve to exclude low income people or functions that are uncongenial to the established residents. This strategy of ‘exclusionary zoning’ is (to my mind) a far more corrosive planning device than relative densities, as it results in artificially homogeneous districts confined to one commercial use or residential profile.
In conclusion, Downs is more concerned with controlling low-density sprawl as a means of reversing inner-city decay than addressing the efficacy of zoning and other regulatory strategies. Indeed a key aspect of his recommendations is the degree to which ‘densification’ should be pursued through further, more draconian regulation “administered by institutions that operate at the same scale as the major problems” . The author readily admits however that the transfer of planning powers to a ‘top-down’ regional or metropolitan body would be resisted both by city authorities and the local population. One suspects it would be even less feasible today, in the era of the Tea Party movement and a general suspicion of all things ‘socialist’. The practicality of Downs’ solution, particularly with respect to housing for the poor, is also undermined by his frequent reference to “massive federal funding” as a prerequisite for success.
As regards zoning, Downs is unclear in his approach: he sees virtue in mixed neighborhoods where the poor are (forcibly) integrated with the middle classes through regulatory intervention; and yet he views it as a bad thing that “suburbs become more urban, assuming more of the functions and services formerly performed only in the central city. Fewer suburban residents need to visit central cities or even to interact indirectly with them.”  In this respect Downs appears to have missed the central point of Peter Calthorp’s book “The Next American Metropolis” (1993) which he reviews in detail. Calthorp’s model for a transit-based development strategy (see diagram below) recognizes the advantage of atomized neighborhoods coexsting within an urban framework (via the transit) but with independent commercial, industrial and residential areas, in other words without a downtown, or centralized employment district, or neatly defined distinctions between the inner city and the suburbs. His vision of a hierarchy of densities in combination with mixed-use zoning appears, to my mind, a more valid urban planning approach than simple densification with strong regulatory intervention.
It is interesting to consider how the issues addressed in “New Visions” have changed in the fifteen years since it was published. Recent studies (reviewed elsewhere on this blog) indicate that some traditional city centers are in the process of regeneration thanks to an influx of young and wealthy ‘urbanites’, whereas outer suburbs, or exurbs, are increasingly home to impoverished families. The attraction of low-density development on the suburban fringe has been further reduced by massive surpluses in the housing stock, record-high gas prices and a growing environmental movement that views such development as ecologically wasteful. In the short term this turnaround has been achieved through market forces rather than regulatory constraints. It is probable that the five aspirations identified by Downs as the cause of urban sprawl remain largely in place, but are dampened by the realities of an energy and environmental crisis that is global rather than national in scale.