What impact did railroads have on America and its national identity at that time?

The railroads were a great advancement in America's history. Before railroads, anyone heading out West, to places like Nebraska or California, did so by horse. This took many weeks, and was quite dangerous. With the expansion of the railroads after the Civil War, this journey took much less time to complete, and became much safer as well. In the years to follow, populations increased dramatically in Western settlements, allowing Americans to occupy much more of the country's vast territory than ever before.

Some other random facts:

1 - American bison populations deplete to near extinction as trains run though grazing area and introduce hunters.

2 - American Indian tribal lands get cut down dramatically as more people move out West.

3 - The railroad economy skyrockets. Companies spring up to make steel, lumber, and especially rail cars.