Answer:
Escaping slaves had to find their way north. Northern states such as New York and Massachusetts had strong abolitionist societies and benevolent groups — both black and white — that would help escaping slaves. The slaves' final goal was Canada, north of the U.S. border. Slavery was not permitted there, and American laws that allowed people to capture runaway slaves had no effect.
People trying to escape slavery had many clues they could rely on to find out where "north" actually was. They knew moss usually grew on the north sides of trees. They also observed that migrating birds flew north in the summer.
One of the best clues they could use to find north was to locate the North Star. The North Star is also called Polaris. Unlike other stars, it never changes position. It always points to the north.