Preface: Admission to the Union is provided by the Admissions Clause of the United States Constitution in Article IV, Section 3, Clause 1, which authorizes the United States Congress to admit new states into the Union beyond the thirteen states that already existed when the Constitution came into effect.

The Constitution went into effect on June 21, 1788 in the nine states that had ratified it, and the U.S. federal government began operations under it on March 4, 1789, when it was in effect in 11 out of the 13 states.

Since 1789, an additional 37 states have been admitted into the Union. Each new state has been admitted on an equal footing with those already in existence.

The fifty stars on the US flag represent the current number of states.

(1) Of the 37 states admitted to the Union by Congress, all but six have been established within existing U.S. organized incorporated territories. A state so created might encompass all or part of a territory.

(2) In many instances, an enabling act would detail the mechanism by which the territory would be admitted as a state after the ratification of their constitution and the election of state officers. Although the use of such an act is a traditional historic practice, several territories have drafted constitutions for submission to Congress absent an enabling act but were subsequently admitted. The broad outline for the process was established by the Land Ordinance of 1784 and the 1787 Northwest Ordinance, both of which predate the U.S. Constitution.

(3) The Admission to the Union Clause forbids the creation of new states from parts of existing states without the consent of all of the affected states and that of Congress.

 
Overseas Territories and Other Areas

(4) Since the close of the Spanish American War in 1899, the United States has obtained several overseas territories. Among these, territories which have been ceded to the United States in a peace treaty after a formally declared war have included the following:

Puerto Rico

Surrender Ceremonies	Peace Treaty	End of USMG	Civil Government status
Aug. 12, 1898	April 11, 1899	May 1, 1900	civil government for Puerto Rico (USA)

Philippines

Surrender Ceremonies	Peace Treaty	End of USMG	Civil Government status
Aug. 14, 1898	April 11, 1899	July 4, 1901	civil government for Philippines (USA)

Guam

Surrender Ceremonies	Peace Treaty	End of USMG	Civil Government status
June 21, 1898	April 11, 1899	July 1, 1950	civil government for Guam (USA)

(5) After conquest by US military forces, the above three territories were recognized to be subject to US administrative authority. With the coming into force of the peace treaty, they were ceded to the United States, and governed according to the procedures established under the US Constitution’s territorial clause (Article 4, sec. 3, cl. 2). For ease of reference, we can refer to these as "Category I Overseas Territories."

(6) On July 4, 1946, the United States announced the Philippines' independence.

(7) However, what most researchers overlook is that the US Supreme Court has recognized another category of overseas territory, which may be more properly called "US overseas quasi trusteeship."

A comparison may be made as follows.

US Overseas Territory

Category of Territory	US Supreme Court Description	Common Description / Nomenclature	Legal Reference
Category I	Domestic territory (Domestic country)	US overseas territory	US Constitution's territorial clause (Article IV, sec. 3, cl. 2)
Category II	Territory under the dominion of the United States and/or "territory held in trust for its inhabitants"	US overseas quasi trusteeship	US Supreme Court rulings in DeLima v. Bidwell (1901), Neely v. Henkel (1901) and other cases

(8) The recognition of the existence of a category of US overseas quasi trusteeship was first made by the US Supreme Court in 1901. This was made based on the legal status of Cuba after the coming into force of the Spanish American Peace Treaty on April 11, 1899.

(9) The criteria which the US Supreme Court used in making this determination may be derived from the historical and legal context of Cuba's situation at that time. Other overseas areas which meet those criteria would of course be fully entitled to recognition as a US overseas quasi trusteeship.

(10) For a more in depth explanation, see this website's detailed overview of DeLima v. Bidwell, 182 U.S. 1 (1901)