Final answer:
The growth of railroads in the 1850s significantly expanded the US economy, altered the social fabric through cultural exchange and migration, and heightened North-South tensions that precipitated the Civil War.
Step-by-step explanation:
The growth of railroads in the 1850s had profound effects on the United States. Firstly, it led to the significant expansion of the economy, as goods and people could be transported more quickly and efficiently across the country. This spurred the rise of new industries and the growth of towns and cities along rail routes. Secondly, the growth of railroads altered the social fabric by promoting cultural exchange and migration. Thirdly, this development heightened tensions between the North and South over economic and political control, eventually contributing to the outbreak of the Civil War.
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