Why were efforts to improve life for Blacks in Northern cities frustrated?

In the 50 years following the end of Reconstruction, African Americans transformed American life once more: They moved. Driven in part by economic concerns, and in part by frustration with the straitened social conditions of the South, in the 1870s African Americans began moving North and West in great numbers. In the 1890s, the number of African Americans moving to the Northeast and the Midwest was double that of the previous decade. In 1910, it doubled again, then again in 1920. In the 1920s, more than 750,000 African Americans left the South--a greater movement of people than had occurred in the Irish potato famine of the 1840s.

Explanation:

abraham lincoln  (february 12, 1809  – april 15, 1865) was an american statesman, politician, and lawyer who served as the 16th  president of the united states  from 1861 until  his assassination  in april 1865. lincoln led the nation through the  american civil war, its bloodiest war and its greatest moral, constitutional, and political crisis.[2][3]  he preserved the  union,  abolished slavery, strengthened the  federal government, and modernized  the u.s. economy.