Answer:
After the last expansion, gold was discovered at Sutter's' Mill, bringing many more Americans from the East, and benefitting them greatly, even bringing in people from outside America. This revolutionized America's economy. Manifest Destiny brought money, land, resources, and a strengthened economy to the Americans.
Explanation:
The columbian exchange had a very negative effect on the Native Americans. The native americans received mostly disease from Europeans, but also certain plants and animals. Syphilis is one thing Europeans contracted from Native Americans.
The critical World War I battles were fought primarily along the trench lines of France and Belgium.
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