First the social part: The war caused a huge division among the American citizens, because many families were forced to fight between them during the Civil War, and that's why the relationship between Northern and Southern states have changed.
Talking about the economic part: there existed millions of dollars in damage the both side. Besides, the Union destroyed railroads and plantations.
The last one is political: A huge divide in the American political structure was caused by The Civil War. A new form of government was created by The Confederate States that left US, and they followed their own rules ignoring the Union requests.
