Answer:
Industrialization.
Step-by-step explanation:
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The industrialization process consists in increasing the production capacity of goods, through the use of machines powered by energy sources. This process requires technological development of industries.
In 1865, the end of the civil war allowed the transition from an agricultural economic model to a model in which the factories took a hegemonic role.
This situation produced an increase in the jobs offered by the industry, which encouraged agricultural workers to emigrate to the cities, increasing in turn the number of inhabitants in them.
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