American Scientist

Technology drives technology, and few things illustrate this on a large scale more dramatically than the evolution of international shipping. For centuries, sailing ships transported cargo that first had to be loaded onto a wagon at its origin, pulled to port by horses, and loaded onto a ship at the dock. After crossing the ocean, the cargo had to be unloaded from the ship and loaded onto another wagon, which transported it to its destination. It was a time- and labor-intensive operation. The advent of the steamship and the railroad made the process somewhat more efficient but did not reduce the number of times the cargo was handled. Indeed, if the delivery location was not near a railroad, another cargo-transfer step was added, from railroad car to wagon.