For much of human history, humans could travel only as far as they could walk. Constructing the famous Roman roads took six centuries. Even then, trade was difficult, and spoilage was an issue. Moving food and other goods over land was especially difficult. Even countries that had breadbaskets could not reliably feed their populations. By the 14th century, “history finally started picking up speed” (112) via boating improvements. Compared to overland transportation, waterways are a relatively cheap and easy way to move goods and people.

However, even with more efficient ships, geopolitics greatly limited trade. Empires would not trade food with one another, and piracy was a constant threat in the trade of luxury items. At the close of the preindustrial era, economies remained either self-contained or subjugated. Little improvement had been made in overland travel.

In the industrial era, railroads were transformative. They could be built anywhere that was relatively flat and reduced the cost of overland transport to only twice that of water transport. Before railroads, Russia could not feed its own population with its grains, but with railroads, Russia sold grain internationally. Water transportation improved greatly in the industrial era, since steel ships could travel faster.