Answer:
The domestic shift that affected the most the demographic make up of northenr US cities in the early 1900s was:
The migration of African Americans from southern to northern factories.
Explanation:
Three reasons make this event the major demographic changer in the U.S. The first one is that immigrants only started to mean a considerable part of the population after the number reached 50000 in 1920. When the U.S. total population was around 70 million. However, the slave population reached 4 million in the late 1960s. Therefore their movement in the U.S. territory would mean a bigger change. The second reason that made it a game-changer was that the majority of the slaves would require suitable conditions to live and work. Therefore they included in northern society was a big change, because it needed to adapt to their migration. The third fact was that their culture was about to change and be shown in northern populations that were not that custom to them, so it would mean a big contributor to diversity.
