How long did it take to build the underground railway?

Answer 1

No time. It wasn't a real railroad, but a series of stops north where the slaves were hidden and given help. Think about this: if it had been a real railroad that the southern slave owners would not have allowed it to be built. As it was the people who hid slaves were breaking the law and were arrested when found. To leave a plantation a slave, had to have a pass and could be asked by any white person to show the pass. ( these were metal disks).

Answer 2

It was not built. It was a series of stops north.