yes there was the underground railroad leading to canada, she DOES understand her question. The slavery took place in the nineteen century and the railroad was used by negroe slaves and a small amount of white slaves. So do your research next time!
slavery ? i think you do not understand your question ! slavery = colonialism mentality (in america ? it has never existed... let's say that it is the word you like today, yesterday it was racism, tomorrow it will be obama-iste...)
l'esclavage en amerique a été aboli par napoléon 1 ! napoléon has prohibited it and all the nations have said no the first day of the discovery of america so it is not slavery, but work whithout to be payed that you meant, i suppose so...