Encyclopedia of the Underground Railroad (E-Textbook)
Fugitive slaves were reported in the American colonies as early as the 1640s, and escapes escalated with the growth of slavery over the next two hundred years. As the number of fugitives rose, the Southern states pressed for harsher legislation that they thought would prevent escapes. The Fugitive Slave Act of 1850 criminalized any assistance, active or passive, to a runaway slave—yet it only encouraged the behavior it sought to prevent. Friends of the fugitive, whose previous assistance to runaways had been somewhat haphazard, increased their efforts at organization. By the onset of the Civil War in 1861, the Underground Railroad included members, defined stops, set escape routes and a code language.