a secret system used in the US before the Civil War for helping thousands of enslaved people to escape to the free northern states or Canada. The people trying to escape were called 'passengers', the people who helped them were 'conductors', and the safe houses used for hiding in along the way were called 'stations' .
شبکه مخفی فرار بردگان, مسیر مخفیانه فرار بردگان, شبکه آزادی بردگان