Admission to the Union is provided by the Admissions Clause of theUnited States Constitution in Article IV, Section 3,Clause 1, which authorizes theUnited States Congress to admit newstates into theUnion beyond thethirteen states that already existed when the Constitutioncame into effect. The Constitution went into effect on June 21, 1788, in the nine states that had ratified it, and theU.S. federal government began operations under it on March 4, 1789, when it was in effect in 11 out of the 13 states.^[1] Since then, 37 states have been admitted into the Union. Each new state has been admitted on anequal footing with those already in existence.^[2]

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 that was so created might encompass all or part of a territory. When the people of a territory or a region have grown to a sufficient population and have made their desire for statehood known to the federal government, Congress in most cases has passed anenabling act, authorizing the people of that territory or region to frame a proposedstate constitution as a step toward admission to the Union. The use of an enabling act has been a common historic practice, but several states were admitted to the Union without one.

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 theLand Ordinance of 1784 and the 1787Northwest Ordinance, both of which predate the U.S. Constitution.

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. The primary intent of the caveat was to give the fourEastern States that still hadwestern land claims (Connecticut, Georgia, North Carolina, and Virginia) aveto over whether their western counties could become states.^[3] The clause has since served the same function each time that aproposal to partition an existing state or states has arisen.

Article IV, Section 3, Clause 1:

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.^[4]

Between 1781 and 1789, the United States was governed by aunicameral Congress, theCongress of the Confederation, which operated under authority granted to it by theArticles of Confederation, the nation's first constitution. The 11th Article authorized Congress to admit new states to the Union provided nine states consented. Under the Articles, each state cast one vote on each proposed measure in Congress.

During this period, the Confederation Congress enacted two ordinances governing the admission of new states into the Union. The first such ordinance was the Land Ordinance of 1784, enacted April 23, 1784.^[5]Thomas Jefferson was its principal author. The ordinance called for the land (recently confirmed as part of the United States by theTreaty of Paris) west of theAppalachian Mountains, north of theOhio River and east of theMississippi River to eventually be divided into ten states. Once a given area reached 20,000 inhabitants, it could call a constitutional convention and form aprovisional government. Then, upon enacting a state constitution which affirmed that the new state would forever be part of the Confederation, it would be admitted on an equal footing with all other states, based on a majority vote in Congress.^[5] Stipulations for new state dictated that it would be subject to the Articles of Confederation and acts of Congress; would be subject to payment for federal debts; would not tax federal properties within the state border or tax non-residents at a rate higher than residents; and would have arepublican form of government.^[5] Jefferson's original draft of the ordinance gave names to the proposed states and contained a provision that "After the year 1800 there shall be neither slavery nor involuntary servitude in any of them."^[6]

The 1784 ordinance was superseded three years later by the Northwest Ordinance of 1787. Enacted by the Confederation Congress on July 13, 1787, it created theNorthwest Territory, the first organized incorporated territory of the United States. The Northwest Ordinance (Article V) provided for the admission of several new states from within its bounds:

There shall be formed in the said territory, not less than three nor more than five States [...] And, whenever any of the said States shall have sixty thousand free inhabitants therein, such State shall be admitted, by its delegates, into the Congress of the United States, on an equal footing with the original States in all respects whatever, and shall be at liberty to form a permanent constitution and State government: Provided, the constitution and government so to be formed, shall be republican, and in conformity to the principles contained in these articles; and, so far as it can be consistent with the general interest of the confederacy, such admission shall be allowed at an earlier period, and when there may be fewer free inhabitants in the State than sixty thousand.^[7]

While the Articles of Confederation were in effect, the Congress considered various ordinances admitting particular new states into the Union, none of which were approved:

• On August 20, 1781, Congress passed a resolution stating conditions under which theVermont Republic (at the time ade facto but unrecognizedsovereign state) could enter the Union. It needed only to give up its claims to territory west ofLake Champlain and east of theConnecticut River.^[8] In February 1782, the legislature of Vermont agreed to those terms. However, Vermont's admission was opposed byNew York, which asserted a disputed claim to the region and consequently successfully resisted the proposed admission.
• On May 16, 1785, a resolution to admitFrankland (later modified to Franklin) to the Union was introduced in Congress. Eventually, seven states voted to admit what would have been the 14th state. This was, however, fewer than the nine states required by the Articles of Confederation. The proposed state was located in what is todayEast Tennessee and within the territory west of theAppalachian Mountains that had been offered byNorth Carolina as a cession to Congress to help pay off debts related to theRevolutionary War. It continued to exist as anextra-legal state through mid-1788, when North Carolina reassumed full sovereignty over the area. In 1790, when North Carolina again ceded the region, the area that comprised Franklin became part of theSouthwest Territory, the precursor to the state ofTennessee.
• In July 1788, Congress began deliberations on whether to admitKentucky to the Union.^[9] Kentucky was then a part ofVirginia. The legislature of Virginia had consented to the creation of the new state from its western district. However, when Congress began to discuss the matter, they received notification thatNew Hampshire had ratified the Constitution, becoming the ninth state to do so, causing it to go into effect in the ratifying states. Congress instead passed a resolution stating that it was "unadvisable" to admit a new state under those circumstances and the matter should wait until the federal government under the Constitution came into existence.

Considered one of the most important legislative acts of the Confederation Congress,^[10] the Northwest Ordinance established the precedent by which the Federal government would be sovereign and expand westward with the admission of new states, rather than with the expansion of existing states and their established sovereignty under the Articles of Confederation. No new states were formed in the Northwest Territory under either ordinance. In 1789, the1st United States Congress reaffirmed the Northwest Ordinance with slight modifications.^[11] The Northwest Territory remained in existence until 1803, when the southeastern portion of it was admitted to the Union as the State ofOhio, and the remainder was reorganized.

At the 1787Constitutional Convention, a proposal to include the phrase "new States shall be admitted on the same terms with the original States" in thenew states clause was defeated. That proposal would have taken the policy articulated in the Ordinance of 1784 and made it a constitutional imperative. Many delegates objected to including the phrase, fearing that the political power of future new western states would ultimately overwhelm that of the established eastern states.

Delegates, understanding that the number of states would inevitably increase,^[12] did agree to include wording into this clause to preclude formation of a new state out of an established one without the consent of the established state as well as the Congress.^[3] It was anticipated that Kentucky (which was a part of Virginia), Franklin (which was a part of North Carolina, and later became part of the Southwest Territory), Vermont (to which New York asserted a disputed claim), and Maine (which was a part ofMassachusetts), would become states. As a result of this compromise, new breakaway states are permitted to join the Union but only with the proper consents.^[13]

Shortly after the new Constitution went into effect Congress admitted Vermont and Kentucky on equal terms with the existing 13 states and thereafter formalized the condition in itsacts of admission for subsequent states. Thus the Congress, utilizing the discretion allowed by the framers, adopted a policy of equal status for all newly admitted states.^[3] The constitutional principle derived from these actions is known as theequal footing doctrine. With the growth ofstates' rights advocacy during theantebellum period, theSupreme Court asserted, inLessee of Pollard v. Hagan (1845), that the Constitution mandated admission of new states on the basis of equality.^[2]

Historically, most new states formed by Congress have been established from an organized incorporated U.S. territory, created and governed by Congress in accord with itsplenary power under Article IV, Section 3,Clause 2 of the Constitution.^[14] In some cases, an entire territory became a state; in others some part of a territory became a state. In most cases, the organized government of a territory made known the sentiment of its population in favor of statehood, usually by referendum. Congress thenempowered that government to organize aconstitutional convention to write astate constitution. Upon acceptance of that constitution, by the people of the territory and then by Congress, Congress would adopt by simple majority vote ajoint resolution granting statehood. Then thePresident of the United States would sign the resolution and issue a proclamation announcing that a new state had been added to the Union. While Congress, which has ultimate authority over the admission of new states, has usually followed this procedure, there have been occasions when it did not.^[15][16][17]

Congress is under no obligation to admit states, even in those areas whose population expresses a desire for statehood. In one instance,Mormon pioneers inSalt Lake City sought to establish the state ofDeseret in 1849. It existed for slightly over two years and was never approved by the Congress. In 1905, leaders of theFive Civilized Tribes (Cherokee, Chickasaw, Choctaw, Creek, and Seminole) inIndian Territory proposed to establish the state ofSequoyah as a means to retain control of their lands.^[18] The proposed constitution ultimately failed in Congress. Instead, the Indian Territory was incorporated into the new state ofOklahoma in 1907.

Some U.S. territories existed only a short time before becoming states, while others remained territories for decades. The shortest-lived wasAlabama Territory at 2 years, whileNew Mexico andHawaii territories both were in existence for more than 50 years. The entry of several states into the Union has been delayed by complicating factors. Among them,Michigan Territory, which petitioned Congress for statehood in 1835, was not admitted to the Union until 1837, because ofa boundary dispute with the adjacent state of Ohio. The independentRepublic of Texas requested annexation to the United States in 1837, but fears about potentialconflict with Mexico delayed the admission ofTexas for nine years.^[19] Also, statehood forKansas Territory was held up for several years (1854–1861) because of a series of internalviolent conflicts involvinganti-slavery andpro-slavery factions.

Once established, most state borders have, with few exceptions, been generally stable. Notable exceptions include: the various portions (the Western land claims) of several original states ceded over a period of several years to the federal government, which in turn became the Northwest Territory, Southwest Territory, andMississippi Territory; the 1791 cession by Maryland and Virginia of land to create theDistrict of Columbia (Virginia's portion wasreturned in 1847); and the creation, on at least three occasions, of a new state (Kentucky,Maine andWest Virginia) from a region of an existing state (Vermont was created from what was disputedly claimed to be a part of New York and was not admitted until New York consented); two large additions toNevada, which became a state in 1864, were made in 1866 and 1867. There have been numerous minor adjustments to state boundaries over the years as a result of improved surveys, resolution of ambiguous or disputed boundary definitions, or minor mutually agreed boundary adjustments for administrative convenience or other purposes.^[20] One notable example is the caseNew Jersey v. New York, in whichNew Jersey won roughly 90% ofEllis Island from New York in 1998.^[21]

In addition to the original 13, six subsequent states were never part of an organized incorporated U.S. territory:

• Vermont, admitted March 4, 1791, was formed from the territory of the Vermont Republic (earlier known as theNew Hampshire Grants). This territory was also claimed by New York. The resulting dispute led to the rise of theGreen Mountain Boys and the later establishment of the Vermont Republic. New Hampshire's claim upon the land was extinguished in 1764 byroyal order ofGeorge III, and on March 6, 1790, the state of New Yorkceded its claim to Vermont for 30,000Spanish dollars.^[22]
• Kentucky, admitted June 1, 1792, wasset off from Virginia (previously its westernDistrict of Kentucky counties). TheVirginia General Assembly adopted legislation on December 18, 1789, separating its "District of Kentucky" from the rest of the state and approving its statehood.^[23][24]
• Maine, admitted March 15, 1820, was set off from Massachusetts (previously theDistrict of Maine, its northernexclave). TheMassachusetts General Court passed enabling legislation on June 19, 1819, consenting to the separation of the District of Maine from the rest of the state (an action approved by the voters in Maine on July 19, 1819); then, on February 25, 1820, passed a follow-up measure officially accepting the fact of Maine's imminent statehood.^[23] The act of Congress establishing Maine as the 23rd state was part of theMissouri Compromise of 1820.^[25]
• Texas, admitted December 29, 1845, was formed from the territory of the Republic of Texas followingthe republic's annexation into the United States earlier in 1845.^[26]
• California, admitted September 9, 1850, was formed fromunorganized territory ceded to the United States byMexico in the 1848Treaty of Guadalupe Hidalgo at the end of the Mexican–American War. The Act of Congress establishing California as the 31st state was part of theCompromise of 1850.^[27]
• West Virginia, admitted June 20, 1863, during the Civil War, was set off from Virginia (previously its northwestern trans-Allegheny region). The General Assembly of theRestored Government of Virginia passed an act on May 13, 1862, granting permission for the creation of West Virginia.^[28][29] Later, by its ruling inVirginia v. West Virginia (1871), the Supreme Court implicitly affirmed that the breakaway Virginia counties did have the proper consents required to become a separate state.^[30]

• 51st state
• An Act for the Admission of the State of California
• Enabling Act of 1802, authorizing residents of the eastern portion of the Northwest Territory to form the state of Ohio
• Legal status of Texas
• Enabling Act of 1889, authorizing residents of Dakota, Montana, and Washington territories to form state governments (Dakota to be divided into two states) and to gain admission to the Union
• Enabling Act of 1906 authorizing residents of Oklahoma, Indian, New Mexico, and Arizona territories to form state governments (Indian and Oklahoma territories to be combined into one state) and to gain admission to the Union
• Alaska Statehood Act, admitting Alaska as a state in the Union as of January 3, 1959
• Hawaii Admission Act, admitting Hawaii as a state in the Union as of August 21, 1959
• Federalism in the United States
• List of U.S. states by date of admission to the Union
• List of U.S. state partition proposals
• Perpetual Union
• State cessions
• Statehood movement in the District of Columbia
• Statehood movement in Puerto Rico
• Secession in the United States

• The Uniting States: The Story of Statehood for the Fifty United States, three volumes, edited by Benjamin F. Shearer, Greenwood Press, Westport, Connecticut, 2004,ISBN 0-313-32703-3

• Article Four of the United States Constitution
• Clauses of the United States Constitution
• Political history of the United States
• Historical geography of the United States
• States of the United States

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