Clayborne Carson, a professor of history at Stanford University, said the greatest impact of Obama’s election will be felt internationally.

Clayborne Carson, a former activist and now a Stanford University historian, remembers getting arrested in 1965 just because he demanded the right to vote. He says it was inconceivable then that the United States would elect an African-American president.

Clayborne Carson, a Stanford professor who is a leading historian of Martin Luther King Jr. and the civil rights movement, said Tuesday's vote for Barack Obama and Proposition 8 reminded him of a similar situation in the 1964 presidential election.

Clayborne Carson said Obama's candidacy — and victory — brought the nation face to face with the question of whether it could succeed as a heterogeneous democracy.