The president pro tempore of the senate can best be described as

Unlike the vice president, the president pro tempore is an elected member of the Senate, able to speak or vote on any issue. ... Since 1890, the most senior U.S. senator in the majority party has generally been chosen to be president pro tempore and holds the office continuously until the election of another.
Hope i helped :)

Well I think the civil rights act of 1964 hasted the end of legal Jim Crow to make sure African American citizens have equal access to restaurants and transportation and other public facilities