Can U.S. states form or join new unions?
<p>The U.S. is presently a country with deep political divisions, which are distributed in part geographically.  One possible resolution is a split into multiple nations; this idea was firmly refuted by the Civil War.</p>

<p>However, another possible solution is to form additional new governments out of existing states.  This would be a governmental layer above the state layer but below the federal layer.  These super-states would represent multi-state regions of more closely aligned political views.</p>

<p>The constituent states would cede some of their authority to these super-state governments, which would then be empowered within their borders to collect taxes, write and enforce laws, etc.  However, neither the states nor the super-states would deny the authority of the Federal government.  The super-states would not be nations, would not form treaties with other nations, and would leave all international policy to the Federal level.  They would also defer to  Federal law when applicable, e.g. the commerce clause.</p>

<p>The benefits of super-states would be similar to the domestic benefits of the federal government, but at a smaller scale.  For example, rather than each state individually setting entitlement/ education/ health/ energy/ environment policy (which has high administrative costs due to duplication), or each state trusting the federal government to do so (which is likely to displease a lot of states due to political divisions), the super-states can set the policy for their constituent like-minded states.</p>

<p>My question is this.  Does the U.S. Constitution or existing legal precedent prevent the establishment of  such super-states?  That is, do states have the authority to transfer their own rights?</p>

<p>Only with the approval of Congress. An agreement between states is called an "<a href="https://en.wikipedia.org/wiki/Interstate_compact" rel="noreferrer">interstate compact</a>" (a variety of existing compacts are listed in the link). </p>

<p>The federal government can also unilaterally create an independent agency with authority in some states, but not others such as the <a href="https://en.wikipedia.org/wiki/Tennessee_Valley_Authority" rel="noreferrer">Tennessee Valley Authority</a> and the <a href="https://en.wikipedia.org/wiki/Appalachian_Regional_Commission" rel="noreferrer">Appalachian Regional Commission</a>.</p>

<p>The relevant parts of the Constitution are Article I, Section 10, which states:</p>

<blockquote>
  <p>1: No State shall enter into any Treaty, Alliance, or Confederation;
  grant Letters of Marque and Reprisal; coin Money; emit Bills of
  Credit; make any Thing but gold and silver Coin a Tender in Payment of
  Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing
  the Obligation of Contracts, or grant any Title of Nobility.</p>
  
  <p>2: No State shall, without the Consent of the Congress, lay any
  Imposts or Duties on Imports or Exports, except what may be absolutely
  necessary for executing it's inspection Laws: and the net Produce of
  all Duties and Imposts, laid by any State on Imports or Exports, shall
  be for the Use of the Treasury of the United States; and all such Laws
  shall be subject to the Revision and Controul of the Congress.</p>
  
  <p>3: <strong>No State shall, without the Consent of Congress,</strong> lay any Duty
  of Tonnage, keep Troops, or Ships of War in time of Peace, <strong>enter
  into any Agreement or Compact with another State, or with a foreign
  Power,</strong> or engage in War, unless actually invaded, or in such
  imminent Danger as will not admit of delay.</p>
</blockquote>

<p>Also relevant are Article IV, Section 3, Clause 1:</p>

<blockquote>
  <p>New States may be admitted by the Congress into this Union; but no new
  State shall be formed or erected within the Jurisdiction of any other
  State; nor any State be formed by the Junction of two or more States,
  or Parts of States, without the Consent of the Legislatures of the
  States concerned as well as of the Congress.</p>
</blockquote>

<p>and</p>

<p>Article V:</p>

<blockquote>
  <p>The Congress, whenever two thirds of both Houses shall deem it
  necessary, shall propose Amendments to this Constitution, or, on the
  Application of the Legislatures of two thirds of the several States,
  shall call a Convention for proposing Amendments, which, in either
  Case, shall be valid to all Intents and Purposes, as Part of this
  Constitution, when ratified by the Legislatures of three fourths of
  the several States, or by Conventions in three fourths thereof, as the
  one or the other Mode of Ratification may be proposed by the Congress;
  Provided that no Amendment which may be made prior to the Year One
  thousand eight hundred and eight shall in any Manner affect the first
  and fourth Clauses in the Ninth Section of the first Article; and that
  no State, without its Consent, shall be deprived of its equal Suffrage
  in the Senate.</p>
</blockquote>

united-states constitutional-law us-constitution