| While the size of the market determines the amount
of service activity within a city, variations are possible; both
from place to place, and in the type of service activity provided.
A city may have more service activity than indicated by the size
of the market, and this surplus of facilities is called "centrality".
A high index value of centrality implies that the city is serving
an extensive region outside the city, as well as its own urban market.
Conversely, a deficiency of service facilities - and a negative
index of centrality - suggests that the city's external role is
quite limited, or that it may even import goods and service from
nearby centres. On the map, the size of the symbol is proportional
to the population of the city, while the index is shown by the colour.
Geographical Description
The map of the index of centrality confirms the differences between
urban and rural locations, with the latter ranking very low in general.
However, note the exceptions in recreation areas such as Squamish-Whistler,
British Columbia (skiing near Vancouver), Muskoka, Ontario (cottage
country north of Toronto) and the Laurentians, Quebec (north of
Montréal). Among the urban centres, the highest indices of
centrality are found in the small urban places that serve extensive
rural areas in the Prairies (such as Grande Prairie, Alberta, Swift
Current, Saskatchewan and the like). The lowest values occur in
the isolated mining and resource towns, such as Kitimat, British
Columbia and Labrador City, Newfoundland and Labrador.
High values of centrality in the prairie region contrast with the
lower values in industrial centres of Ontario and Quebec. At the
same time a number of specialized distribution centres surround
Toronto and Montréal. In the West, almost all cities provide
services for nearby trade areas. In the Atlantic region, the larger
centres have high values, but smaller cities are specialized in
mining or forestry, with low centrality. Rural and urban differences
in centrality are very strong, as are the differences among the
suburbs of the larger consolidated metropolitan regions such as
Toronto and Montréal. Some suburbs specialize in services;
others are largely residential.
To properly interpret this map, please consult the text Data
and Mapping Notes.
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