Tubman was never content with being free unless everyone else was, too. She vowed to return to the plantation and bring her family and friends to freedom. And for the next 10 years, she made more than a dozen trips to Maryland to free slaves, according to the National Park Service.
She made her first trip back in 1850, when she discovered that her niece, Kessiah, was going to be auctioned off. First, she came up with a plan with Kessiah's husband, a free man. Then, she guided them through the Underground Railroad, a secret network of routes and safe houses, after he bought his family at the auction, according to Biography.
Tubman used the skills she learned while observing the stars and working in the fields and woods to guide people to freedom. She also gave instructions to slaves who eventually found their way to freedom. She later claimed to have never lost a passenger on the Underground Railroad.
And when Congress passed the Fugitive Slave Act of 1850, which allowed authorities in non-slave states to capture and return escaped slaves to their owners, Tubman helped reroute the Underground Railroad to Canada.
She took her last trip to Maryland in 1860. While some say Tubman rescued 300 people during her trips, the Harriet Tubman Underground Railroad Byway puts the number closer to 70.