The two main sources of congressional authority in the field of foreign affairs lies in Article I and Article II. The phrase <span>"advise and consent" are the two pillars of the powers of the Congress regarding foreign affairs. I hope that this is the answer that has actually come to your desired help.</span>
The Underground Railroad was the name of the escape routes used by slaves to escape the South and flee to the North. It was a network of special routes and safe houses that were used by both slaves and abolitionists who were sympathetic to their cause of escaping slavery. It started in the late 1700's and ended after the abolition of slavery. Canada was a popular destination, as slavery was prohibited their and had a longer border for easier access.
Positive--resulted in the lowering of the voting age to 18, contributed to the end of the Vietnam War, contributed to furthering the civil rights movements of the time.
Negative--they were violent and led to the deaths of many in riots and shootings, their means were not taken seriously by adults and conservatives of the time,