A National Historic Site designation is being sought for the Indianapolis park where Robert Kennedy called for peace and unity just hours after the assassination of Martin Luther King Jr.

The entire Indiana congressional delegation has signed a letter to the U.S. interior secretary seeking the designation for Dr. Martin Luther King Jr. Park that's just northeast of downtown Indianapolis. Bills have also been introduced in Congress to establish the Kennedy-King National Historic Site.

The park is where Kennedy was to make an April 1968 presidential campaign speech, but instead told the crowd of King's assassination and asked for a nonviolent reaction.

U.S. Sen. Joe Donnelly says the historic site would highlight continued efforts to celebrate diversity and equality as source of strength for the country.