What do you think the biggest problem facing the untied states after the civil war was?

Helping the South

Explanation:

After the civil war ended, the South was almost completely destroyed, plantations and crops were burnt down and Confederate money became worthless. Most of the North wanted to punish the South for what they did, however, it was important to Lincoln that the South could easily rejoin. He was assassinated and Andrew Johnson became president, who was from the South. The Union rebuilt roads, got farms running again, and built schools for poor and black children, this obviously would have cost a lot of money, and the North had been effected by the civil war as well as the South.

a is the final : )