48 Hein de Haas
more general political-economic processes. If migration policies do not
match economic realities, the usual result is irregular migration.- The existence of substantial differentials in economic and social oppor-
tunities between sending and receiving countries seems to be a conditio
sine qua non for large-scale migration to occur. When such differentials
decrease substantially, migration is likely to decrease, and the other way
around. However, such factors cannot explain the actual migration pat-
terns we see, with highly specialised f lows between, for instance, the
Emirdag region of Turkey and Belgium, or the Rif area of Northern Morocco
and the Netherlands. - The preponderance of Turkey and Morocco in European immigration
conf irms the hypothesis derived from transitional-migration theory
that very little ‘South-North’ migration occurs from the least-developed
countries, as well as the fact that geographical proximity probably plays
an important role too.^6 - The evolution of Turkish and Moroccan migration to Western Europe,
and Egyptian migration to the Gulf region and Libya, demonstrates
that, once migration systems are established, migration movements
gain their own momentum, partially or even largely independent of their
immediate causes. Initial migration patterns tend to be reproduced,
partly because of the internal social and economic dynamics inherent
to the migration process itself, giving rise to migration systems that link
places in countries of origin and destination through relatively stable
exchanges of people, goods, capital (remittances), ideas and information.
In particular, migrant networks tend to facilitate continuing labour,
family and undocumented migration over formally closed borders (Mas-
sey et al. 1998). Because of these self-reinforcing dynamics, migration
tends to follow historical migration patterns. Thus, current migration
patterns cannot be explained without taking into account the regional
political-economic forces majeures of the past, the initial patterns of
labour recruitment or initial journeys of ‘spontaneous’ pioneer migrants,
who still leave their ‘footprint’ on actual migration patterns through the
functioning of migrant networks.
6 In fact, geographical proximity to Europe and levels of socio-economic development seem
to be correlated, and it is likely that both factors are reciprocally related.