Following the U.S. Civil War, the Radical Republicans attempted to put a land reform through Congress, promising, 40 acres and a mule, to newly-freed blacks in the South, which was rejected by moderate elements as socialistic. This failure left blacks without an economic base, and was one of the key contributing factors to the development of sharecropping and segregation.
The Ice Age had a great effect on where people settled in americans since they were only able to reach North America through the Bering Land Bridge, which was only frozen due to the extremely low temperatures. Without this they would have had no way to leave Siberia.