The Underground Railroad was a network of secret routes and safe houses used in the 19th century to help enslaved African Americans escape to free states and Canada. It was not a physical railroad but rather a series of paths and safe locations where abolitionists and sympathizers provided assistance. Key figures in the Underground Railroad included Harriet Tubman, who made numerous trips to rescue enslaved individuals, and various abolitionist groups. The network operated from the early 1800s until the Civil War, playing a crucial role in the fight against slavery and helping thousands achieve freedom.