Final answer:
The growth of railroads in the United States led to increased migration west of the Mississippi River.
Step-by-step explanation:
One effect of the growth of railroads in the United States was increased migration west of the Mississippi River. The railroads made it easier for people to travel long distances, leading to a surge in westward migration as people sought new opportunities and land. The railroads facilitated the settlement of the western frontier, connecting the East Coast to the newly opened territories.
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