The significance of the Fourth of July for blacks was the subject of an 1852 speech delivered the day after the holiday by Frederick Douglass to a white audience at Rochester, New York’s Corinthian Hall.
In his speech, Douglass points out that slavery is inconsistent with the principles set forth by the Declaration of Independence. He told his audience, “This Fourth of July is yours, not mine. You may rejoice, I must mourn.”
What, to the American slave, is your 4th of July? I answer; a day that reveals to him, more than all other days in the year, the gross injustice and cruelty to which he is the constant victim. To him, your celebration is a sham; your boasted liberty, an unholy license; your national greatness, swelling vanity; your sounds of rejoicing are empty and heartless; your denunciation of tyrants, brass fronted impudence; your shouts of liberty and equality, hollow mockery; your prayers and hymns, your sermons and thanksgivings, with all your religious parade and solemnity, are, to Him, mere bombast, fraud, deception, impiety, and hypocrisy — a thin veil to cover up crimes which would disgrace a nation of savages. There is not a nation on the earth guilty of practices more shocking and bloody than are the people of the United States, at this very hour.”
You can read the entire speech here, and you can also listen to a portion of it being read by James Earl Jones here.