Each day countless commuters trek through the commuter zone to the CBD, from T3 to T6, from “MSA but not in a central city” to “central city of an MSA,” from residential subdivision to financial district, from sparsely populated to densely populated, and from suburban to urban core. These are just more technical terminologies for describing the prototypical work commute from an outlying bedroom suburb to the center of a nearby city. Commute time from suburb to central city all depends on the size of the city and metropolitan area, geographical barriers, roadway networks, access to mass transit, traffic congestion, and so on. However, commute time may also depend on the amount of land consumed by each degree of urbanicity, or the classification of the landscape by the type of built environment that it holds. Since the built landscape is not a solid continuum, several methods of categorization have been established.
The built environment houses various building types, densities, networks, land uses, and functions. A typical highway drive into an American urban center from outside of its most far-flung fringe communities begins in the natural areas and rural vistas of forestland, mountains, farmland, and cattle ranches. As the city approaches within the present-day metropolitan area, the landscape begins to show signs of more permanent, non-agricultural settlement patterns. Especially near major highways, residential subdivisions of single-family homes, townhomes, and condominiums emerge in almost random clusters. Next arrives a denser, more continuous type of built environment where a more intense network of roadways and transportation supports tightly-packed rows of single- or multi-family homes, clusters of commercial development, office complexes, and light industry.
Closer to the urban core lies intact street-oriented neighborhoods of high density housing such as rowhouses, mid-rise apartment buildings, mixed-use retail-residential buildings, heavy industry and manufacturing plants, as well as more intensified commercial development. The center of the city boasts an entirely street-oriented class of buildings whose densities far eclipse that of any surrounding areas. Office and apartment towers, heavy industrial uses, transportation hubs, regional government offices and medical care facilities, as well as major entertainment venues make up the core of the urban complex. The core is a major employment, entertainment, civic, transportation and living center wrapped into one incredibly dense central area. In most major cities across America, the entire spectrum of the built environment is traversed by car in less than an hour. The description just employed is based off of a more recent urban planning model that divides the built environment into six parts. Before that model is revealed, however, it is helpful to understand the beginnings of built landscape classifications and how the urban-rural continuum is defined by government entities.