The Civil War had an enormous effect on industry in the North. As a result, it helped change the U.S. from a country that was farm centered and plantation-centered to one that was mechanical and was reliant on the market system. Before the civil war there was only a small industry in the North. During the summer of 1860, the US had 128,300 companies registered as industry. New York and Pennsylvania the most industry.
On the down side, many of the African Americans who had been slaves went back to work doing the same thing they had been doing before; however they got paid. Not necessarily with money but by obtaining land rights for their modest homes. Howver the playing field was slightly better for African Americans because they had "some" rights. Of course, the later civil rights movement built on the successes of the civil war.
Some African Americans moved to the north where they were treated better than in the south. Since industry had grown there were more jobs there, so their economic situation improved.