Explain why the railroad and steel industries were interdependent during the 19th century?

I'm most likely gonna be wrong on this but correct me if i am wrong

Explanation: farmers demanded regulation of railroads because it was expensive and they sold to other businesses than other settlers so they profited from it.

That's what I could think of so basically it was a way to gain more money in the end.

I hope this helped

a. factors that are used to make goods and services