What is the importance of the "Underground Railroad" in the novel, Who Comes with Cannons?

The Underground Railroad figures prominently throughout Who Comes with Cannons? It represents hope for people like Squire; it is part of their service to God and humanity for the Bardwell's and Truth. A "station" on the Underground Railroad is a hiding place where escaped slaves can get help and be moved to the next "station." No one at any of the stations knows of any other stations except the ones immediately preceding and following theirs; the implication is clear: If caught none of the people of the stations can be forced to tell where all the stations are. They have no idea where more than three of the stations could be. The atmosphere is almost like that of a police state. Strange armed men burst into houses, searching where they please and threatening the inhabitants with harm. Young men like Robert and Todd can be beaten up just because people suspect they may having something to do with helping people become free; women like Truth can be abused and molested simply for being associated with ideas that the state opposes. It is no wonder Robert fears a twelve-year-old girl toward whom he should be kind. Any outsider is an enemy, because an outsider might tell the law where to find the slaves.