The Underground Railroad "was an informal network of secret routes and safe houses used by 19th century Black slaves in the United States to escape to free states and Canada with the aid of abolitionists who were sympathetic to their cause. The term is also applied to the abolitionists who aided the fugitives. Other various routes led to Mexico or overseas. Created in the early nineteenth century, the Underground Railroad was at its height between 1850 and 1860. One estimate suggests that by 1850, 100,000 slaves had escaped via the "Railroad". Canada was a popular destination with over 30,000 people arriving there to escape enslavement via the network at its peak, though US Census figures only account for 6,000."