Fugitive slaves fleeing from Maryland to Delaware by way of the 'Underground Railroad', 1850-1851. The Underground Railroad was a secret organisation set up in the northern United States in defiance of the Fugitive Slave Acts to help slaves who had escaped from their owners. An estimated 40,000-100,000 slaves made use of the system between 1830 and 1860. (Photo by Ann Ronan Pictures/Print Collector/Getty Images)
