People freely left “ethnic” neighborhoods even where there was no influx of blacks. The GI Bill caused the first wave of flight as why would you be stuck in a two or three family old home when you could get a single family on the crabgrass frontier cheap with a low interest loan. In the case of my father’s neighborhood, his once German neighborhood became a Polish neighborhood when his grandparents moved in. As the Poles moved to suburbia, Portuguese immigrants came in. As the Portuguese moved out due to upward mobility, Brazilians and Ecuadorians moved in. This was ironically in a city that become majority black otherwise in the 1960s.