Huh?? What kind of a question is that? United States can be singular or plural or both. Which one??
On the voter registration form in Massachusetts it tells you to swear, under the pains and penalties of perjury, that you are a United States Citizen and sign your name affirming that you are a citizen. That registration form is a binding contract between you and the United States. Under the law governing contracts the parties must fully understand the contract as to what is required in the contract and what the benefits are.
Did you understand and were you fully informed of the details of that contract?? I strongly doubt it.
Have you ever studied Law?? Were you educated in government schools as to what the legal term United States is defined as. Did the voter registration form tell you which United States you were swearing you were a citizen of? Did you know that the Supreme Court in the case of Hooven & Allison Co. vs. Evatt says there are 3 different definitions of United States and in most cases it only means the Federal Zone or District of Columbia which is not the land territory of the several States that make up The united States of America, a union of separate Nation States. DC is a separate city State like the Vatican or inner city of London. The District of Columbia in legal terminology is "foreign" to the rest of the united States of American.
In international law "United States" refers to a sovereign nation under the jurisdiction of the President through his agents or agencies such as the Dept. of Sate.
Under Federal law jurisdiction and on Federal law forms it usually means The District of Columbia, all territories (like Puerto Rico) and enclaves ( Federal parks, military bases, Federal buildings) owned by the Federal government
Under the Constitution for the united States of America it means the land of the 50 separate States (perhaps not Alaska or Hawaii) .
Your natural born rights attach to the land and your "civil" rights (really permissions) come from government ( see the 13th amendment to the American Constitution which only has "subjects to the laws") .
Now that you see there is a difference of meaning, which one on the voter registration form was meant and which one did you believe it meant? If you didn't know or still don't know you signed a contract without understanding what you were doing and still don't
You can be a natural born citizen of say, Tennessee, which qualifies you as a human being born on the land of Tennessee with certain Rights outlined in the Tenn. and American Constitutions ( A Tenn. National and an Amer. National). You can have dual citizenship as an American National and of the Federal Territory. You can be exclusively a citizen of the District of Columbia and not an American National or you can be solely a Tennessee National without being a citizen of DC also known as the United States ( usually all in caps. UNITED STATES or UNITED STATES OF AMERICA). Once you have sworn you are a United States citizen on Federal Forms or in verbal affirmations before a court that has a different jurisdiction other than the American Constitution, you are permanently considered to be a citizen and a subject ( or subjugated ) to the Federal Government without the protection of your unalienable rights in the Constitution .
There are many examples of State and Federal forms that show primary evidence that you gave up your Constitutional rights to subjugate yourself to a corporate and or commercial jurisdiction with no stinkin' Constitutional Rights.