The boom in railroads contributed to the industrialization of the nation in some very important ways. It led to a huge increase in the demand for steel and it allowed a host of industries to grow which relied on the railroads to get their raw materials and their finished goods to and from their factories.
As the railroads boomed, demand for steel skyrocketed. Steel was needed for tracks and for rolling stock. This helped the steel industry to grow, driving industrialization. At the same time, the railroads allowed other industries to grow. Industries were now able to move huge quantities of raw materials to factories just about anywhere in the country. They could then move the finished goods around the nation equally easily.
In these ways, the railroads contributed in tremendous ways to the industrializtion of the US.