II.

Market Areas

Central place theory also involves the distance people are prepared to travel to obtain particular functions. This distance, known as the range of the good or the range of services, determines the size of a settlement's market area, that is, the area inhabited by most of the people who use its services. The higher the order of a central place, the larger its range. Therefore, places with only lower-order functions will have a very limited market area and their residents will need to travel further to higher-order central places to obtain higher-order functions.

Christaller theorized that across a more or less flat landscape with evenly spaced settlements, or isotropic plain, market areas would be hexagonal in shape with the settlements in the centre of the hexagons. This is because hexagons interlock neatly, whereas circular areas would leave some parts of the plain unserved. However, in reality settlements are of different orders, with higher-order settlements competing to encompass lower-order ones within their market areas. Because of this, various, often complicated hexagonal structures of settlement patterns can develop. For example, a pattern consisting of just two orders of central places—rather than the seven that Christaller distinguished—would result in the central positioning of the higher-order settlements in relation to adjoining market-area hexagons. According to Christaller's theory they will each be surrounded by six lower-order settlements positioned according to three main patterns. Firstly, the lower-order central places may be positioned on the six points of the hexagon surrounding the higher-order central place; in the case of a landscape honeycombed with adjoining hexagons, this would mean that each lower-order place would be competed for by the three adjoining higher-order central places. Secondly, the lower-order central places could be positioned in the centre of the sides of the hexagon, which would mean they were in the market areas of the two adjoining higher-order central places. Finally, all the lower-order central places could be contained within the market-area hexagons of the higher-order central places. The kind of complicated pattern that can develop with more than two orders of central places is illustrated on the left-hand side of the diagram.