240 Modern Business Geography Manufacturing industries located at markets. Just as perishable and bulky raw materials determine the location of some manufacturing industries at the source of supply, so perishable and bulky finished products determine the location of others at the market where they are consumed. The baking industry is usually located in the cities where its products are sold. Newspaper printing is carried on close to the market. Both bread and news grow stale if allowed to get old through transportation. Farming machinery is an example of a finished product whose bulk causes it to be manufactured near its market. Huge, awkward ma- chines like wheat harvesters or threshers occupy so much car space that there is a decided advantage in manufacturing them near the center of the market. A third kind of manufacturing carried on at the market is a response to the particular needs of certain industries. Anchors, for instance, are made at Gloucester, Massachusetts, because the deep-sea fishermen require a special type in their work. A more important example is found in Detroit, where hundreds of factories turn out ball bearings, bolts, springs, axles, batteries, self-starters, fans, and other parts of automobiles in order to meet the special needs of the chief industry of the city. How the labor supply affects the location of manufacturing plants. Manufacturing is possible only where there are plenty of laborers, both skilled and unskilled. This is one reason why cities attract manufacturing plants. The lack of skilled labor, on the other hand, is one of the chief causes of the scarcity of manufacturing plants out- side the temperate zone. Some industries, like the making of ready-to-wear clothing, require a great supply of cheap labor. Hence New York and Boston are sspecially prominent in such industries, because they have a constant supply of immigrants. Other cities depend more largely upon skilled labor. The shoe industry and the making of fine textiles are of this kind. Both maintain their firm position in the northeastern United States partly because of the presence of skilled workers. Sometimes an industry flourishes in one place and not in another because of an unused labor supply. The silk industry is a striking illustration of this. In order to be profitable, it must have a large number of women who work for low wages; few men are required. Therefore silk weaving is located in places where large numbers of men are already employed in work like iron and cement making, which require cheap and heavy labor. Their wives and daughters, being