Stories: The Underground Railroad: Mamie Sweeting Diggs in Williamsport

February was Black History month. But the history of the African-American experience in Pennsylvania is too rich--and too important--to be confined to one month per year. So, this month, WPSU offers a special three-part series: An audio tour of some Pennsylvania stops on the Underground Railroad. In Part two, we travel to Williamsport, where two stops on the railroad are gone, but the memory lives on. WPSU's Cynthia Berger reports.