Commodity rates as a means for enabling shippers to reach beyond their immediate territory and gain an entrance to new markets, form an entirely distinct variety of charges from those quoted in the classified tariffs. These are special rates made to suit particular contingencies,[351] although, of course, under the law they must be filed with the Interstate Commerce Commission in the same manner. Such commodity rates, however, do not apply to persons but to localities. Although granted to shippers in a particular place to build up an industry, the privilege of shipment under the same conditions is theoretically open, of course, to all others at that point. Such commodity rates naturally apply to three sets of commercial conditions: they either govern large shipments for long distances, as in the case of live stock; or, if for short distances, they are confined to commodities of the very lowest grade, such as lime, sand or paving blocks; or else they are introduced to meet special conditions, such as an irregular market or rapidly fluctuating competitive circumstances, as in the case of goods for import or export. Such special rates are almost invariably granted for carload lots alone. The reason is, naturally, that it would not be worth while to make an exception to the classified schedules for less than that amount. Moreover, it should be observed, special rates of this sort are often introduced in order to meet changeable competition, such as by steamship lines engaged in export or import business. The classified ratings change but little, and oftentimes remain the same for many years. But in all cases where fluctuating conditions have to be met, commodity rates by the carload are likely to appear. This is one reason why the transcontinental tariffs, exposed to competition either by the Cape Horn or Panama water routes, contain so large a proportion of commodity or carload ratings.[352]