The enigma of the Underground Railroad was that it was neither underground nor was it a railroad. It was in fact a loose network of people, black and white, who would assist an escaped slave who took the initiative to liberate him or herself from bondage. It was fluid in route going where ever there was hope of assistance a free black settlement in a rural area, a religious group, an ethical person, a free thinker, or a free black community in an urban area. An escaped slave would travel any direction that would lead to freedom. It changed across time as people became indignant over the implications of slavery in society or as people could no longer physically do the work of helping people to escape.
The Underground Railroad seems to have depended on trust. Trust that other blacks would shelter the slave that had stolen themself to freedom; trust that kinship networks would provide shelter from town to town. Trust that peers of like mind, passion, temperament, or reason would rise to the occasion to break Federal law to help a human being in need. It was a secret so well guarded that parents would not tell their families about their involvement with it, or a secret that was so poorly guarded that it was flaunted as part of a media war for the hearts and minds of their neighbors while trying to fan the flames of abolitionism.
There are primary sources documenting work on the Underground Railroad contrary to the myth that it is impossible to research. There were very few secret passages, hidden rooms, or tunnels despite legends and myths to the contrary. There are not nearly as many secrets in code, sign, or symbol despite the best effort of internet sources to create a legendary past. The Civil War did not end the Underground Railroad; it ended when the last state adopted the 13th amendment to the U.S. Constitution. It was unsuccessful in purging the nation of slavery, but it was successful in helping individuals find freedom in a new land.