Which event resulted directly from the growth of railroads in the 19th century?

Beginning in the early 1870s, railroad construction in the United States increased dramatically. ... Between 1871 and 1900, another 170,000 miles were added to the nation's growing railroad system. Much of the growth can be attributed to the building of the transcontinental railroads.

Explanation:

The Civil War was the defining event for nineteenth-century America, and railroads played an important role in the conflict. As the North industrialized rapidly between 1820 and 1860, railroads helped create --and prospered from -- the rise of factory production and diversified large-scale agriculture.

b]to spread the message of black power