It was a law which was passed which provided southern slaveholder to capture slaves who would escape.
The Immigrants settled in Cities because Jobs were readily available.
Answer:
When the Soviet Union's oil and gas revenue dropped dramatically, the USSR began to lose its hold on Eastern Europe. Meanwhile, Gorbachev's reforms were slow to bear fruit and did more to hasten the collapse of the Soviet Union than to help it. ... On December 25, Gorbachev resigned as leader of the USSR.
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