Final answer:
Since the 1940s, the percentage of the U.S. population employed in manufacturing has sharply decreased, with a decline of over a third since the late 1970s. This trend signifies the country's transition from a manufacturing-based economy to a service-oriented one.
Step-by-step explanation:
The percentage of the population employed in manufacturing since the 1940s has significantly declined. In the 1950s, the United States produced 40 percent of goods and services worldwide, but this figure shrank to 25 percent by the 1970s. It's also noted that manufacturing jobs peaked in the late 1970s and have since declined by more than a third. The United States has seen a shift toward a postindustrial service economy, with a noticeable increase in service sector jobs over the past 50 years, while industrial jobs, particularly in manufacturing, have trended downwards.
The decline in manufacturing jobs has had associated social and economic impacts, such as the decline of union membership and the rise of part-time and contract labor. Many manufacturing jobs have been outsourced to countries with lower labor costs, contributing to the job loss in the sector within the United States. Significant changes in the manufacturing landscape first became apparent by the 1970s when the U.S. started importing more goods than it exported, reflecting the shift from a predominantly manufacturing-based economy to a service-oriented one.