The Underground Railroad of the 19th century was neither underground nor a railroad, but a network of clandestine routes and safe havens assisted by abolitionists, Native Americans and Quakers to help slaves escape into free states such as Canada and Mexico. Workers on the Railroad were known as 'conductors' such as ex-slave Harriet Tubman, known as 'Moses' as she never lost a fugitive when guiding them to their freedom.
It is suggested by some historians that quilts were used as a secret communication device using various patterned symbols, indicating specific information to help guide slaves during their escape along the many routes of the Underground Railroad. These symbols were shown subtly by the seamstress and memorized by the slave.
Secret code communication also appeared aboard the slave ship in various forms, such as singing. Male and female slaves, who were usually separated on board, would sing in their native language, communicating to find fellow villagers, identify cultural groups and organise insurrection unbeknownst to the European sea captains the majority of the time.