Toward what audience does MLK direct his "I Have a Dream" speech, and how does he appeal to this audience with specific quotes or examples?

Martin Luther King, Jr. directs his "I Have a Dream Speech," delivered in Washington, D.C. on August 28, 1963, to the entire nation, but his use of "we" referred to the nearly 250,000 people gathered at the capitol for the March on Washington for Jobs and Freedom. The speech was intended to express their support for the civil rights legislation proposed in June of 1963 by President Kennedy. He also addresses the nation as a whole.

At the beginning of his speech, King says, "In a sense we've come to our nation's capital to cash a check." His reference is to the promises of the "Emancipation Proclamation" of 1863, a full century earlier, and to the unfulfilled promises of the "Declaration of Independence" for African-Americans. He appeals to his audience by referring to seminal events in American history to suggest that this march, and its call for civil rights, is a continuation of these critical events that shaped the destiny of the United States. His words have echoes of those of Lincoln. For example, "Five score years ago" is similar to Lincoln's "four score and seven years ago" in the "Gettysburg Address." King's words also recall those of Jefferson: "life, liberty, and the pursuit of happiness."

King also uses the traditional African-American preaching technique of voice merging, or adapting the words of religious leaders in the past. When King says, "We can never be satisfied," and uses a series of examples of the way in which African-Americans are not equal, including police brutality and the lack of the vote, he is merging his voice with that of Amos, the Old Testament preacher who said "Let justice roll down like waters." Amos's prophetic voice merges with the prophetic voice of King in an example of voice merging. In addition, King's famous anaphora (use of repetition) at the end of the speech, which repeats the phrase "I have a dream," calls on the words of Isaiah in the Old Testament. Isaiah referred to the valleys exalted, mountains laid low, which are words echoed in King's words: "I have a dream that one day every valley shall be exalted and every hill and mountain shall be made low, the rough places will be made plain."  This is another example of voice merging. 

Therefore, King's speech first establishes political authority by calling on Jefferson and Lincoln, and then moves to religious authority and the use of a prophetic voice. At the end of the speech, King again uses political authority by calling on references to "My Country 'tis of Thee," also known as "America." His use of anaphora with the repetition of "let freedom ring" in the states of Georgia, Tennessee, and Mississippi (then known as one of the worst states with regard to civil rights) is a powerful reminder that freedom does not exist in these states.