Background

Metropolitan expansion is a dynamic process, and official classification systems have to be flexible enough to accurately represent changes in a nation’s settlement structure (Fuguitt et al., 1988). Accordingly, the US metropolitan statistical areas system has been reviewed periodically since the county-based metropolitan area concept was first introduced in 1950. The system’s first review was completed in 1958, and subsequent studies have typically followed each decennial census. In 1990, the US Office of Management and Budget initiated the latest and most fundamental review of its standards for classifying the nation’s population with respect to metropolitan residence. The Metropolitan Concepts and Statistics Project was prompted by concerns that the existing classification system was overly complex, and burdened by ad hoc criteria. Moreover, there was concern that the existing standards were poorly understood and frequently used in inappropriate ways. A decade of study, including extensive research by the US Census Bureau, commissioned papers by several well known social scientists, and abundant public comment culminated in December 2000 with the OMB’s announcement of its new standards (Office of Management and Budget, 2000).

Counties were retained as the basic geographic building block even though many social scientists recommended compiling metropolitan areas from sub county units (Morrill et al., 1999). In contrast, OMB instituted a new core based statistical system which significantly changed other aspects of the nation’s statistical geography. As Fitzsimmons and Ratcliffe (2004: 354) have noted,“large urban centers have both form and function,” and the new core-based system marginally changed the way form is determined by population size and density, while significantly changing how the extent of a city’s integrative function is measured.