The railroad system in the U.S. was the ideal instrument for the terrain:  a large geographic country with its population concentrated on its ocean coasts, and with three vertical mountain ranges cutting its farming plains into distinct climactic areas, only the railroad could unite it.  First, the good and supplies needed to sustain a population could be shipped from the east coast into the newly settled areas.  Then, as crops become products to ship to the east coast for consumption, railroads served as an efficient and economical means.  Finally, as the natural resources of the country—coal, metal ores, etc.—were extracted from the mountains themselves, only the railroad system, becoming a spider web of access to all parts of the diverse landscape, could move bulk items of this nature, creating markets and competition.  The 19th and early 20th centuries, then, became a time of rapid expansion, because the railroads could overcome the size and ruggedness and diversity of the country.  By the time the railroads became people-transportation, the country’s physical development was well on its way:  river transportation moved products and materials north and south, but only the railroad could connect all of the U.S. together.  Since the railroads owned a mile or so of land on either side of the tracks they laid, they became rich landowners as well.  The novel, The Octopus, by Frank Norris, demonstrates the process (it takes place in 1901) and in impact on all society that the railroads had.