Final answer:
By the end of World War II, the United States was manufacturing 50% of all manufactured goods globally, which included a significant portion of the world's automobiles. However, by the 1970s, America's share of global goods and services production, including cars, declined to 25%, with increased competition from Japanese manufacturers.
Step-by-step explanation:
The question relates to the historical production of automobiles, specifically regarding the percentage of the world's cars produced by America by the end of a particular decade. The relevant information can be found within the context of America's industrial history and its manufacturing capabilities over time. While the question does not specify which decade is being referred to, there are various historical points to consider.
During World War II, America's wartime production soared with factories converting from consumer goods to military equipment production. By the end of the war, the United States was manufacturing 50% of all manufactured goods globally. This included a significant portion of the world's automobiles, as by the 1920s, mass production of automobiles had greatly expanded, increasing mobility and fostering new industries.
However, by the 1970s, the share of global goods and services produced by the United States had fallen to 25 percent, with the post-war decades witnessing various changes, including the rise of foreign competition in the auto industry, especially from Japanese car manufacturers like Honda and Toyota. By the end of the 1970s, the trend had shifted, and America's dominance in car production was challenged by imports and an increase in intra-industry trade.