What was a push factor in the great migration apex?

the answer is jim crow laws for APEX

Africans-Americans were escaping racial segregation, known euphemistically as Jim Crow

The black southerners held on to the believe that racial segregation was less intense in the north. in the southern side, the failures of reconstruction policy to protect them, had left them severely exposed to racial prejudice, bias, lynching and series of laws that made the African-Americans socially, economically and politically oppressed.