Central Place Theory - The Importance of A City and Other Theoretical Considerations

The Importance of A City and Other Theoretical Considerations

According to Smith, Walter Christaller erred in his development of CPT in 1930 by using size of population and number of telephones in determining the importance of a city. Smith recognized that although population size was important to the area served by a city, the number of kinds of services offered there was more important as a measure of the importance of a city in attracting consumers. In applying CPT to describe the delivery of medical care in California, Smith counted the number of physician specialties to determine the importance of a city in the delivery of medical care.

Christaller also erred in the assumption that cities "emerge". In California and much of the United States, many cities were situated by the railroads at the time the tracks were laid. In California, towns founded by the railroads were 12 miles apart, the amount of track a section crew could maintain in the 1850s; larger towns were 60 miles apart, the distance a steam engine could travel before needing water. Older towns were founded a day's walk apart by the Spanish priests who founded early missions.

In medical care regions described by Smith, there is a hierarchy of services, with primary care hopefully distributed throughout an area, middle sized cities offering secondary care, and metropolitan areas with tertiary care. Income, size of population, population demographics, distance to the next service center, all had an influence on the number and kind of specialists located in a population center. (Smith, 1977, 1979) For example, orthopedic surgeons are found in ski areas, obstetricians in the suburbs, and boutique specialties such as hypnosis, plastic surgery, psychiatry are more likely in high income areas. It was possible to estimate the size of population (threshold) needed to support a specialty, and also to link specialties that needed to cooperate with each other, such as hematology, oncology, and pathology, or cardiology, thoracic surgery and pulmonology.

The distribution of medical care in California followed patterns having to do with the settlement of cities. Cities and their hinterlands having characteristics of the Traffic Principle (See K=4 above) usually have six thoroughfares through them—the thoroughfares including highways, rivers, railroads, and canals. They are most efficient and can deliver the lowest cost services because transportation is cheaper. Those having settled on the market principle (K=3 above) have more expensive services and goods, as they were founded at times when transportation was more primitive. In Appalachia, for example, the market principle still prevails and rural medical care is much more expensive.