Final answer:
The growth of railroads in 19th century America led to national unity, economic efficiency, and a national market system, cementing railroads as the primary means of national transport and communication.
Step-by-step explanation:
The growth of railroads in the United States during the 19th century had a profound impact on the nation's economy and social structure. Advantages of railroad consolidation included the standardization of procedures and equipment, which facilitated national unity and economic efficiency. Towns and cities deeply desired the economic prosperity that came with being connected to the rail network, often leading to political and governmental involvement in the development of the expansive transportation system.
Railroads became the nation's first "big business," spurring growth in related industries such as iron, wood, coal, and stimulating technological advancements like car couplers and air brakes. This resulted in an increased volume of goods and passengers transported across the nation. By the close of the 19th century, rail lines reached nearly every corner of the United States, serving as the backbone of a national market system. The railroad and telegraph made governance over the vast landscape feasible, hence consolidating American influence and catalyzing trade.