As you all probably know, Harriet Tubman was the face of the Underground Railroad. And it wasn't actually an underground railroad. Also, Harriet Tubman wasn't the only one who went back and forth to save slaves, there were many other "conductors" (that's what they called them) helping out.
Harriet Tubman went back and forth a total of 19 times. She saved over 300 slaves, and used her shotgun to threaten those who wanted to go back to their masters. Did you know that there was a reverse Underground Railroad? There was. In northern states, people kidnapped black men and women, hid them in barns and such, until they could be taken into the South.
One way the Underground Railroad influenced the U.S. is that once the African Americans were set free, they fought for the other African Americans freedom. This helped a lot.
It was one of the big events that showed that African Americans should be set free. Now I'm going to show you some conductors, Harriet Tubman not included.
Sources
google.com
pathways.thinkport.org
historynet.com
americancivilwar.com