This article examines the social dimensions of urbanism in the contemporary United States. A central thesis is that a rural-urban distinction is no substitute for an assessment of the basic dimensions of inter-urban variation. Toward this end, eight factors are compared and interpreted as to total variation explained and mean interrelationship holding other factors constant. The results indicate a slight predominance for the demographic factor, but a relatively small range of difference among the dimensions. The article concludes by suggesting that the demographic aspect of urbanism has been exaggerated, and tentatively considers whether historical and cultural forces influence the structure of urbanism.