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Admission of New States

Last Updated: 2006

Under the Articles of Confederation, the original 13 states were “admitted” to the union based on what historian Peter Onuf calls the “doctrine of state succession.” That is, these new states formed in confederation with one another would succeed the colonies, largely maintaining the territorial boundaries that had existed prior to the American Revolution as well as the existing laws and authority of the colonies. Beyond the original thirteen states, the ability to admit new states belongs to the U.S. Congress and the federal government as is spelled out in the U.S. Constitution.

As a practical matter, however, the Constitution is vague as to the criteria for admission. Given this, Congress would rely on the preconstitutional precedents for statehood admission set forth in the 1787 Northwest Ordinance. Defining guidelines for the admission of the territories of the Northwest as states, the Ordinance declared that new states were to be admitted on equal footing as existing states, allowed for the formation of governed territories, and provided that upon reaching the population threshold of 60,000 free people, a territory could submit a state constitution to the Congress for approval and statehood admission. Although the ordinance says little about the economic situation of the territory, it became an important criterion for potential states; Congress expected the potential state to be not only independent and prosperous, but also beneficial to the country. The Northwest Ordinance not only governed the admission of states of the Northwest, but also served as the precedent for future statehood decisions.


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.

As the United States underwent efforts at territorial expansion under its policy of Manifest Destiny, the governing of new territories and the admission of new states would continue to occupy the national government. Moreover, given that statehood brings with it at least one seat in the House of Representatives, two seats in the Senate, and at least three votes in the Electoral College, strategic partisan calculations have played key roles in statehood decisions. Indeed, after more or less consensus-oriented statehood admission decisions in the first decade of the republic, critics noted that the regional and partisan motivations of the Louisiana Purchase were laid bare by Thomas Jefferson’s extraordinary move.

Such partisan and especially regional motivations came to dominate national statehood decisions. With slavery increasingly dividing the United States’ North and South, and with neither southern nor northern interests wanting to cede representational and Electoral College advantages to the other side, statehood admission politics boiled down to a system of interregional compromise whereby one free state would be admitted alongside one slave state. Free state Indiana’s admission in 1816 was closely followed by Mississippi’s admission in 1817, and Illinois’s and Alabama’s were paired for admission in 1818 and 1819 respectively. And, when Missouri sought admission, the free state of Maine was carved out of Massachusetts in order to offset any southern advantage.

As regional tensions heightened from the eve of the Civil War to Reconstruction, the potential for interregional compromise was limited. Emerging as early as California’s admission in 1850, a new pattern of seeking regional and partisan advantage took hold. From 1850 to the end of reconstruction in 1876, Republicans succeeded in admitting eight new states. Often assessing the party composition of a candidate for statehood admission, Republicans used their advantages and the lack of Democratic and southern voices in Congress to admit even those states that had not yet met the population requirements of the Northwest Ordinance. This pattern was maintained throughout state admissions politics of the nineteenth century as Republicans turned an Electoral College victory, as well as a narrow House majority and an expanded Senate majority, into six new states admitted in 1889 and 1890 alone.

That Congress could create and admit new states conveyed a supremacy of the national government over both the new states as well as the old. As historian Peter Onuf observed, “If new states were equal to the old states, old states would be equal to the new, and thus share in their diminutive character. Statehood defined in these terms was not only compatible with a stronger union: it demanded one” (Onuf 1982, 459).

SEE ALSO: Northwest Ordinance of 1784Northwest Ordinance of 1787

DelawareDecember 7, 1787
PennsylvaniaDecember 12, 1787
New JerseyDecember 18, 1787
GeorgiaJanuary 2, 1788
ConnecticutJanuary 9, 1788
MassachusettsFebruary 6, 1788
MarylandApril 28, 1788
South CarolinaMay 23, 1788
New HampshireJune 21, 1788
VirginiaJune 25, 1788
New YorkJuly 26, 1788
North CarolinaNovember 21, 1789
Rhode IslandMay 29, 1790
VermontMarch 4, 1791
KentuckyJune 1, 1792
TennesseeJune 1, 1796
OhioMarch 1, 1803
LouisianaApril 30, 1812
IndianaDecember 11, 1816
MississippiDecember 10, 1817
IllinoisDecember 3, 1818
AlabamaDecember 14, 1819
MaineMarch 15, 1820
MissouriAugust 10, 1821
ArkansasJune 15, 1836
MichiganJanuary 26, 1837
FloridaMarch 3, 1845
TexasDecember 29, 1845
IowaDecember 28, 1846
WisconsinMay 29, 1848
CaliforniaSeptember 9, 1850
MinnesotaMay 11, 1858
OregonFebruary 14, 1859
KansasJanuary 29, 1861
West VirginiaJune 20, 1863
NevadaOctober 31, 1864
NebraskaMarch 1, 1867
ColoradoAugust 1, 1876
North DakotaNovember 2, 1889
South DakotaNovember 2, 1889
MontanaNovember 8, 1889
WashingtonNovember 11, 1889
IdahoJuly 3, 1890
WyomingJuly 10, 1890
UtahJanuary 4, 1896
OklahomaNovember 16, 1907
New MexicoJanuary 6, 1912
ArizonaFebruary 14, 1912
AlaskaJanuary 3, 1959
HawaiiAugust 21, 1959


Nolan McCarty, Keith T. Poole, and Howard Rosenthal, “Congress and the Territorial Expansion of the United States,” in Party, Process and Political Change in Congress: New Perspectives on the History of Congress, ed. David W. Brady and Mathew D. McCubbins, 392–451 (Stanford, CA: Stanford University Press, 2002); Peter S. Onuf, “From Colony to Territory: Changing Concepts of Statehood in Revolutionary America,” Political Science Quarterly 97, no. 3 (Fall 1982): 447–59; and Charles Stewart III and Barry R. Weingast, “Stacking the Senate, Changing the Nation: Republican Rotten Boroughs, Statehood Politics and American Political Development,” Studies in American Political Development 6 (1992): 223–71.