The great migration was the relocation of of 6 million plus African Americans. Due to harsh segregation laws and a non satisfying economy, these African Americans left the rural south to the industrial north, land ownership in the Midwest, and job opportunities of the west from 1916 to 1970. The north had more opportunity for factory work due to the outcome of World War I and the creation of the assembly line by Henry Ford in cities like Detroit. Jim Crows laws and policies of the south were in place during the post reconstructive era from 1877 onward and the highest amount of lynching was in the 1920s. This was the height of K.K.K. racism and overall American nativism.
http://www.history.com/topics/black-history/harlem-renaissancehttp://www.history.com/topics/black-history/great-migration
The great migration was also the cause of the Harlem Renaissance which was a literacy, artistic, and intellectual movement in NYC. This was an opportunity for African Americans living in harsh conditions and laws to migrate to the north and start new lives. As they started new lives this movement featured new ideas and expressions of culture allowed to them by freedom of speech through music, art, and poetry.