Throughout the years of slavery while most whites were in favor of it there were some that were totally against it. The small groups who want to see slavery abolished were both black and white. As a result a network was developed to help African 
Americans escape to places where they would be safe like Canada and some of the states that had abolished slavery. This network was dubbed the underground railroad. It was comprised of developing safe routes for escape and providing housing along the way.
There is no doubt that this network was successful and laid a path to freedom for many slaves. It is indicated that when it was in full operation that about 1,000 slaves a year were able to make successful use of it.
The secrecy of this network was able to be upheld because it was organized in small groups. Those involved only were aware of what role they were to take in aiding with an escape and were not privy to the entire plan. This made if much more difficult to be infiltrated.
Many people both black and white risked their lives for the sake of the underground railroad.