Final answer:
The percentage of Americans in the middle class increased significantly due to economic growth in the 1950s. However, since the 1970s, there has been a decline in the middle class size and wealth, posing a threat to the country's high standard of living.
Explanation:
The percentage of Americans in the middle class increased greatly as a result of economic growth during the 1950s. Consumerism and economic success in the 1950s led to a surge in the middle class, with almost 60% of Americans being part of it by the mid-1950s.
The decline of the middle class has been a concerning trend since the 1970s, with wealth becoming more inequitably distributed and the size of the middle class decreasing. The shift from spending on needs to wants, fueled by advances in credit and consumer demand for new products, played a significant role.
This decline in the middle class size and wealth presents a significant threat to the high standard of living in the United States, with real GDP per person experiencing fluctuations over the years, leading to periods where people were becoming poorer on average, not richer.
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