How was the underground railroad succesful?

Question

How was the underground railroad succesful?

Answer 1

They came back above ground.

Answer 2

in New York we call it the subway

Answer 3

Harriet Tubman is credited with starting the "underground railroad" to help get runaway slaves from the south to the relative safety of the northern states.

A clandestine operation comprised of relatively "safe" routes of travel, almost always after dark, and a series of "safe houses" along the way, where those desirous of their freedom could rest and eat by day, only to continue the treacherous journey the next night.

This was a very dangerous proposition for those providing aid and comfort or acting as guides, as they ran the risk of being lynched.  Not so the re-captured slaves.  In as much as they were deemed to have "monetary" value to the slave owner, they were returned to their massahs.  Many were "hobbled" upon their return, where ankles were broken to prevent another "run".