How did western settlement affect the railroads themselves?

It didn't affect them at all.

The railroad was a huge factor in developing the west. Matter of fact, cities grew up around the railroad stations. Workers came from the east to find work in the west. Goods were shipped to the west for the people who were making their homes there. Many people who were victims of prejudice in the east went out west to gain employment. Mining was an enormous boost to the economy and they needed the railroads to transport their goods. In a sense the railroad was built on the mining industry. Of course, the west changed with all the influx of settlers. It became more civilized. I hope I didn't over wrote hehe but I hope this helps xD!