Final answer:
The secret method by which fugitive slaves reached Canada was known as the Underground Railroad, a series of secret routes and safe houses that helped slaves escape to freedom.
Step-by-step explanation:
The secret method by which fugitive slaves reached Canada was known as the Underground Railroad. This extensive network was not a literal railroad but a series of secret routes and safe houses that slaves used to escape to Northern free states and Canada. The network's participants, known as conductors, included a diverse group of individuals like free-born blacks, white abolitionists, and Native Americans, as well as involvement from religious organizations such as the Quakers and Methodists. At its peak between 1850 and 1860, it is estimated that about 100,000 slaves may have escaped using the Underground Railroad.