Linkages are the glue which hold urban systems together: economic linkages. Cities as centres of manufacturing and service delivery. Supply chain is scattered globally: the emergence of large industrial metropolises, specialization of cities in particular industries. Helps explains growth rates b. c of specialization ie car production in. Ottawa: differences in rates of growth due to specialization. Classifying manufacturing places (4: components or types of goods, durable goods, non-durable, value-added, high value added (technology, electronics, low value added (textiles, furniture) This is b. c cost of production is also added: stage in the production process, processing of raw materials. Car door: assembly/integration of parts into finished products. Oriented: ultimately firms would seek the lease-cost locations. Ii: but model is idealized or simplistic , characteristics of global economic system, single world market with production for exchange, spatial divisions in organization of the system, existence of a defined core and periphery.