Answer:
The end of the Civil War was won by the Union and, therefore, Lincoln decreed the abolition of slavery, a measure that came into force in 1865. In the same year, the president was assassinated by a southern fanatic. The southern states were devastated by the war and thus became economically and politically weakened.
By abolishing slavery and serving the interests of the North, these states managed to bring great economic development to the country, turning the United States into a great capitalist power. On the other hand, freed blacks were not supported by any government program to integrate into society.
