Many went on to Canada, where they could not legally be retrieved by their owners.
A trip on the Underground Railroad was fraught with danger.
Events such as the Missouri Compromise and the Dred Scott case drove more anti-slavery advocates to take active roles in helping to free slaves.
A damper was thrown, however, when Southern states began seceding in December 1860, following the election of Abraham Lincoln to the presidency.
For this reason, Levi is sometimes called the president of the Underground Railroad.
The eight-room Indiana home they owned and used as a "station" before they moved to Cincinnati has been preserved and is now a National Historic Landmark in Fountain City near Ohio’s western boundary.
In keeping with that name for the system, homes and businesses that harbored runaways were known as "stations" or "depots" and were run by "stationmasters." "Conductors" moved the fugitives from one station to the next.
The Underground Railroad’s "stockholders" contributed money or goods.
A story claims "Mammy Sally" marked the house Abraham Lincoln’s future wife, Mary Todd Lincoln, lived in while growing up was a safe house where fugitives could get meals, but the story is suspect.
The term Underground Railroad began to be used in the early 1830s.