Answer:
Because former slaves fled south to the north.
Step-by-step explanation:
Even after the liberation of the slaves, the Southerners still treated them poorly, did not see them as free people, and continued with the old slave practices they had always had. Because of this, many former slaves fled from the south to the north of the country in search of better living conditions and less prejudice. For this reason, after the American Civil War, northern cities saw an increase in population .