ABSTRACT
The third development tier is the spatial extension of the first two tiers: in some areas it is a direct expansion into contiguous areas so that there is no real dividing line between core and core extension. In other areas, it is an outlier, physically far from core areas but nevertheless intimately tied to them through patterns of investment, trade and population transfers. Some of the areas included in this tier are experiencing rapid economic growth, others have shown stagnant, even negative, growth; some areas are highly urbanized, others are much less so, but are urbanizing rapidly. Often only part of a country is included under this development tier: Brazil, China, India or Mexico certainly cannot be considered as consisting of a single development region, even at the global level. Intra-country differences have largely been ignored up to this point as, even where such differences existed, the strength of the state and national institutions appeared to justify their consideration as a single unit. From here onward, this assumption will often not be possible and there will be a continual tension between the need to look at only one part of the state and the need to consider certain types of information which are available only at the level of the state.
