Complex sentence: Nearly 400,000 migrants, both African American and European American, came to Detroit from the Southeastern United States from 1941 to 1943; there were severe housing shortages and the migrants competed for space and jobs, as well as against recent white European immigrants and their descendants.
Split into simpler sentences: Nearly 400,000 migrants, both African American and European American, came to Detroit from the Southeastern United States from 1941 to 1943. The city had severe housing shortages and the new migrants competed for space and jobs, as well as against white European immigrants and their descendants.