<human>:  What were major demographical shifts after the US Civil War?
<bot>: The US Civil War led to a major shift in the demographics of the United States. After the war ended, many African Americans were freed from slavery, leading to a dramatic increase in the Black population. Additionally, many Southern states saw a decrease in the share of its white population as many people migrated West in search of economic opportunities. The population of newly freed African Americans also grew rapidly as more people moved from rural to urban areas. Finally, the post-war period saw a significant increase in the number of immigrants seeking economic opportunities in the United States.