How can you put Martin Luther King's "I Have a Dream" speech into perspective with the Declaration of Independence?

These two documents are among the most famous (and arguably the best) expressions of the ideals of American liberty. Perhaps the best way to put the speech into perspective with respect to the Declaration of Independence is to consider the ways that King himself references the Declaration. Early in the speech, King observes that the United States was founded on an ideal of liberty that can be traced to the Declaration and the Constitution. He compares these documents to a "promissory note":

When the architects of our republic wrote the magnificent words of the Constitution and the Declaration of Independence, they were signing a promissory note to which every American was to fall heir. This note was the promise that all men, yes, black men as white men, would be guaranteed the unalienable rights of life, liberty, and the pursuit of happiness.

Unfortunately, King says, the nation has "defaulted" on this "promissory note" inasmuch as it has denied the rights to life, liberty, and the pursuit of happiness to its African American citizens. King frames the civil rights movement as an attempt to "cash the check" that was made out to all American citizens. In other words, he calls on the United States to make good on the promises it made in its founding documents and to live up to its ideals. In the most famous (extemporaneous) section of his speech, he says that his "dream" is that the nation will "rise up and live out the true meaning of its creed" that "all men are created equal." So aside from King's astonishing oratorical skills, the famous "I Have a Dream" speech is in many ways remarkable for its insistence that the nation live up to the ideals its founders claimed as its basis.
https://teachingamericanhistory.org/library/document/i-have-a-dream/