The United States and the Soviet Union emerged as superpowers after World War II.
The United States and the Soviet Union were allies during the war. Together, these countries along with other nations brought about the downfall of Hitler's Third Reich. At the end of the war in 1945, these two countries became world super powers.They emerged as the most powerful states in the world. When the war ended, the United States and the Soviet Union had very different ideas of how Europe should be restructured.
"The South had more immigrants in large cities" was not a reason for the growing division between North and South after 1820, since the North had far more immigrants.
