Answer:
fostered iron production and the telegraph industry
Explanation:
The growth of railroads in the 1850s led to formation of new industries, like telegraph communications, and massive production of iron. This because, the locomotive train and railroad or rail tracks employed majorly iron in its construction.
Also, the use of telegraph became popular as a means of sending messages resulting from movement of people over large or far distance caused by the emergence and growth of railroads in the United States.