Why dont we have dukes and earls?

The granting of such titles by the government of United States has been illegal since our country's inception. The U.S. Constitution (Article, I Section 9, clause 8) states: "No Title of nobility shall be granted by the United States; and no Person holding any Office or Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State."