In 1855, a man named Joseph slipped away at night from the Missouri plantation where he was enslaved, crossed the Mississippi River to Cairo, Illinois, and boarded an Illinois Central train bound for Chicago. The man who claimed to own him, Thomas Rodney, followed him north and lost him in Chicago. Rodney then sued the railroad for selling Joseph a ticket. That lawsuit reached the Illinois Supreme Court, which ruled that Black people in Illinois were presumed to be free, so a railroad didn't need proof of freedom to sell someone a ticket. Southern Illinois historian Darrel Dexter will tell Joseph's story at 2 p.m. Saturday at Bloomington Public Library, alongside a statewide traveling exhibit on the Underground Railroad.