The past matters because it affects the present, and we can make serious errors of judgment when we ignore this fact. In studying the past, however, we should try to view it in its own terms and not simply in the light of current concerns. This will not only make for better history, but may be useful in broadening the terms of contemporary debates. These themes are illustrated in terms of the twentieth-century North American city. The influence of the past, and the errom of judgment caused by ignoring its effects, can be seen in Toronto. There, in the postwar era, the health of the central city and the viability of public transit have been attributed to good planning and urban governance. In fact, these features are partly the unintended consequences of the way the urban area developed in the first half of this century. The limitations of viewing the past in terms of the present are illustrated by the way that scholars have allowed current concerns to shape our conception of cities in the first half of this century. For example, the sharp distinction of city from suburb and the search for the origins of the modern land development industry have narrowed our vision of urban areas before World War II. The case of housing policy indicates that this narrowing has not only distorted our view of the past, but also has compelled us to reinvent mechanisms of housing provision, such as cooperatives and self-help, that had been attempted decades ago and subsequently forgotten.The function of the historian is neither to love the past nor to emancipate himself from the past, but to master and understand it as the key to the understanding of the present. E. H. Carr, What is History?As urban historical geographers, we regularly find ourselves in a dilemma. On the one hand, we like to tell our colleagues, who are mostly interested in what is happening now (or tomorrow), that the past matters. We are convinced that the history of any city has shaped its present form and, hence, the types (and degree) of problems it faces. With this understanding, we would like to offer useful insights and tips about current urban problems. The problem is that we are wary of claiming that history offers obvious precedents or lessons. After all, the past is not just a prologue to the present; it is, as L. P. Hartley once observed, "a foreign country" where people do things differently (cf. Lowenthal, 1985). If it is unwise to ignore the past, it is surely foolish to copy it or to draw simple-minded inferences from earlier mistakes. What, then, can it teach us? Does it matter, and if so, how?These are large questions of broad relevance, and they can be answered in various ways. Focusing upon the experience of Canadian and US cities in the twentieth century, in this article we make a two-stage argument that may appear paradoxical. We claim that the past matters for the present, but often not in ways that can be captured by present-day assumptions and categories. Our first point-that the past matters-is the more straightforward, and in the first half...