Answer:
US population distribution changed between the Civil War and the 1920s in a process known as "Great Migration", in which many African Americans migrated from the south to the north of the United States.
Explanation:
When the Emancipation Proclamation was signed in 1863 less than eight percent of African-Americans lived in the northeastern or midwestern states of the United States. As late as 1900 ninety percent of blacks lived in formerly slave states. The majority of this population would migrate to New York, Philadelphia, Boston, Buffalo, Baltimore, Minneapolis, Detroit, Chicago, Milwaukee, Kansas City, Columbus, St. Louis, Pittsburgh, Cincinnati, Cleveland and Indianapolis, as well as many small industrial cities like Gary, Dayton, Toledo, Youngstown, Peoria, Muskegon, Omaha, Newark, Flint and Albany.
Between 1910 and 1930 the black population of the United States grew 40% in the northern states, concentrating this increase in the big cities such as Chicago, Detroit, New York, and Cleveland. This increase was greater during the 1910-1920 period. As the demographic changes occurred in the cities, there was an increase in tensions between African-Americans and the last remittances from European immigrants. Both groups came from eminently rural societies and disputed jobs and housing with the preexisting white working class. The majority of racial problems in this period were found among Irish descendants who defended their jobs from the competition of more recent immigrants and black internal immigration.
In the south the departure of hundreds of thousands of African-Americans reduced the percentage of the black population over the total. For example, in Mississippi, the black population fell from 56% to 37% between 1910 and 1970 and in South Carolina, the percentage fell from 55% to 30% in the same period.
