The Unerground 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 routes led to Mexico or overseas. The Underground Railroad was at its height between 1810 and 1850. One report estimates that up to 100,000 people escaped enslavement via the Underground Railroad., but census figures only account for 6,000.