Underlying geographies of agglomeration are thus physical, historical,
socio-cultural and economic factors and processes. In the case of
the latter, for example, economies of agglomeration flow from the
economies of scale that are gained by certain functions clustering
together – sometimes referred to as ‘traded interdependencies’. There
are also ‘untraded interdependencies’, that is to say, benefits (positive
externalities to use economics jargon) which geographic proximity brings
that cannot always be strictly measured. Amin and Thrift (1994) identify
three sources of such interdependencies: (1) face-to-face contact; (2)
social and cultural interaction which establish networks of trust; and (3)
enhancement of knowledge and innovation. Underlying such ideas is
the notion that human beings are essentially social animals who depend
on the benefits that interaction with others yields. There is no direct
evidence to suggest that this human social and organizational trait is
diminishing in the age of the current communications revolution.