Emmett Till and Mamie Till-Mobley and Roberts Temple National Historic Site Act This bill establishes the Emmett Till and Mamie Till-Mobley and Roberts Temple National Historic Site in Illinois as a unit of the National Park System. The purpose of the site is to preserve, protect, and interpret (1) the Great Migration, (2) the memorial service and funeral of Emmett Till, (3) the courage and activism of Mamie Till-Mobley, and (4) the civil rights movement. The National Park Service shall prepare a general management plan for the site.