How important were the railroads in opening up the American West?

Although other factors contributed greatly the the spread of American civilisation across the Plains, the railroads were incredibly significant for three main reasons:
1. The railways, specifically the Pacific Railroad, provided a catalyst to the boom of the cattle industry. The railroads eliminated the need for the perilous cattle drives over miles of wasteland, instead cattle carts could be used fro safe and convinient transportation.
2. It encouraged people to go West. There was no longer the risk associated with travelling along the beaver trails which were plagued with native American attacks, robbery, disease and a whole host of other reasons as to why you'd much rather stay at home. The railroad was considerably safer and made the promise of cheap land for Homesteaders much more accessible.
3. The railroad companies were given the incentive of two miles of land either side of the tracks they installed. This led the companies to sell off the land for incredibly low prices after construction.