摘要：Several studies of urban growth, based on the 1971, 1981, and 1986 censuses of Canada, suggest that some fundamental changes have occurred in the economic structure of Canada's urban communities since the early 1970s. In particular, research carried out at the University of Toronto's Centre for Urban and Community Studies has aimed at documenting the differential growth rates in the various sectors of the national economy and the growth or decline of particular urban areas (Hooper et al. 1983; Simmons and Bourne 1989). These studies and others have pointed out very clearly that many urban areas have local economies that are highly specialized in a limited number of economic activities and therefore are very vulnerable to swings in the economic pendlllum.
