Transportation. Any product an individual, household, or community does not produce on their own, they must acquire from somewhere else and have it transported. This principle remains true for basic necessities, desirable items, or luxuries. Transport thus stands as an essential mechanism of any economy. Efficiency and reliability of delivery in turn are necessary for a functioning economic system to flourish and grow. Three basic types of transport existed in the Roman world: by boat across a sea, by boat along a river, or by cart across land. Land transport was the most expensive, costing five to ten times what river transport cost. River transport in turn could cost five times as much as sea transport, so Roman businessmen tried to use water transport as much as possible. For example, merchants would use several different rivers to reach their...