United States Constitution, Article I, Section 9, paragraph 8 states:
No title of nobility shall be granted by the United States: and no person holding any office of 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.
Article VI, paragraph 2 states:
This Constitution, and the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any State to the contrary notwithstanding.
The prohibition on titles of nobility was a carry over from Article VI of the Articles of Confederation:
No State, without the consent of the United States in Congress assembled, shall send any embassy to, or receive any embassy from, or enter into any conference, agreement, alliance or treaty with any King, Prince or State; nor shall any person holding any office of profit or trust under the United States, or any of them, accept any present, emolument, office or title of any kind whatever from any King, Prince or foreign State; nor shall the United States in Congress assembled, or any of them, grant any title of nobility.
Ergo, individual states can't acknowledge or grant titles of nobility any more so than the federal government may as they are held to the supreme law of the land, the Constitution, which strictly forbids it. A foreign government or head of State/Royal/Noble House, who holds sovereignty and may confer a title, may do so to a US citizen in spite of residency or citizenship status; however, no government of the United States or any individual State or locality may officially recognize that title and at no time may any officer (elected or appointed) of the United States or any individual State or locality accept that title of nobility while holding that office. Federal and state governments acknowledge the use of an honorific for meritocratic use (Doctors for PhDs), gender identification (Mister/Mistress, Sir/Ma'am), or professional identification (Honorable for certain political offices, Doctor for medical doctors, or Esquire for attorneys), but it is strictly optional in any event. Of course, if you name your child "Sir Edward" or "Prince William", then "Sir" or "Prince" is not an honorific associated with a title, but instead a part of your name.