The greatest asset owned by the american people proved also to be their greatest obstacle. Before them lay a vast continent, most of it still unexplored as the nineteenth century opened. In an age when land was the principal source of wealth, there seemed no end to the promise offered by this enormous expanse of territory. But how to get at it? The celebrated expedition of Meriwether Lewis and William Clark (1804–6) gave Americans their first important clue as to just how vast and varied the western landscape was. For more than a century, however, they could reach land even close to them only by foot or horse, and sometimes by water. But if they traveled by river, they could not return the same way because boats could move only downstream. Going by horse or wagon required roads, which scarcely existed westward and became impassable in winter or wet weather.

Transportation and communication held the key to settling and exploiting the American continent. New technologies in both areas enabled settlers and businessmen alike to conquer time and space in unique ways, and in the process turn wilderness into civilization.