There are perhaps a few dozen books which I frequently cite when I'm involved in discussions of subjects I find interesting. Of that few dozen I consider maybe a dozen books essential reading within their scope of interest.
When considering the development of the American Downtown, its rise, decline, and future prospects, I can't think of a more essential resource than Downtown: Its Rise and Fall, 1880-1950 by Robert M. Fogelson.
One thing which makes this book essential to activists who are attempting to influence the vitality and form of our cities is the extent to which it serves as a counterbalance to wishful thinking and nostalgia. And the primary means by which it accomplishes this is by maintaining its national scope through local examples as it focuses on issue after issue. It wasn't necessarily poor individual policy decisions by Detroit, or Philadelphia, or St. Louis (or Atlanta, Tampa or LA for that matter) which led to the declines. The declines were part of a powerful national tendency, which affected all cities across the country, even those few which came out of the post WWII period with reasonably functional cores. Fogelson's narrative is presented in a relentless fashion, as those policies intended to save downtown often sped up the decline, and those policies which might have at least stemmed the tide failed to be implemented.
The specific issues taken up in the book include the dispersal of residences from the core, the effort to build subways in various cities across the country, the beginning of decentralization of business, the efforts to impose height limits on buildings, the battles over onstreet parking (and the rise of the parking meter), attempts to retrofit downtown with limited access highways in order to make it easier to drive downtown(and how that actually backfired from the vantage point of many of its most vigorous supporters), the formation of the Urban Land Institute, the impact of the tenement reform movement, and the beginnings of the urban renewal programs and federally funded public housing.
I've actually read this book cover to cover more than once, in addition to using it as a reference work, and each time I read it I want to cry. And in some ways that is the value of Fogelsons' work. Since I am a person with a lifelong love of dense, rich, teeming urban life, with it's diversity of experiences and of cultures, with thousands of amenities accessable with a walk or a bus or train ride, I view it as absolutely essential that urbanists in general and New Urbanists in particular have an accurate understanding of the real manner in which the core of our great cities developed and declined. If we don't we are quite likely to produce mirror images of the mistakes of the past, rather than making sure that the cores of our cities are vital and durable for the centuries to come.