Final answer:
The Industrial Revolution is a primary macro-level factor in U.S. history that significantly shaped families, driving a transition from agricultural work to industrial labor and reducing family sizes due to urban living constraints.
Step-by-step explanation:
One of the best examples of a macro-level factor in U.S. history that shaped families would be the Industrial Revolution. This significant event caused a significant shift from agriculture to industry and greatly influenced familial structure. Households were previously self-sufficient, with most labor taking place on the family farm. The Industrial Revolution, however, created a new class system where people moved to urban environments to work in factories. This change necessitated smaller family sizes due to the limitations of urban living spaces, altering the average family size and structure significantly.
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