To begin, it didn't promote "peace" as much as it promoted a "cold war" which is the whole point of the name, Cold War.
Nuclear Weapons essentially forced the US and the Soviet Union into an uncomfortable draw.
They knew they couldn't fight each other directly so they fought each other in a series of devastating proxy wars around the world.
The Supreme Court case that found the use of the grandfather clause unconstitutional is the Guinn v. United States, 238 U.S. 347 (1915). In its decision, the Supreme Court ruled that the grandfather clause<span> exemptions to </span>literacy tests<span> were unconstitutional. It declared the grandfather clauses as </span><span>repugnant to the Fifteenth Amendment and therefore null and void.</span>
Simple. The Columbian Exchange exchanged diseased, people, plants, food, and animals. The Americas adapted with new plants and animals like cattle, chicken, etc., and more slaves. Europe gained potatoes, tomatoes, corn, squash, punpkin, etc.
New societies could depend on new sources of food, new animals. That also improved their local economy, and knowledge (learning)
Answer: 370.97 people per square mile.
Explanation: If you divide population by the amount of square miles, you should get this answer.