Final answer:
The early focus of American industrial mass production during World War I was on ammunition.
Step-by-step explanation:
The early focus of American industrial mass production to prepare the country for World War I was on ammunition. As the war escalated, there was a high demand for weapons and munitions, and American factories began producing massive amounts of ammunition to support the war effort. This was necessary to equip and supply the soldiers on the front lines with the necessary weaponry.
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