States and Their Admission to the Union

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The thirteen original colonies in North America could officially be admitted to the United States after the U.S. Constitution was written and signed by the delegates to the Constitutional Convention, on Sep. 17, 1787. Article IV, Section 3 of that document reads:

"New States may be admitted by the Congress into this Union; but no new States 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."

The main part of this article grants the U.S. Congress the right to admit new states. The process usually involves Congress passing an enabling act that authorizes a territory to convene a constitutional convention, draft a constitution, and formally apply for admission. Then, assuming they meet any conditions set forward in the enabling act, Congress accepts or denies their new status. 

Between Dec. 7, 1787, and May 29, 1790, each of the colonies became states. Since that time, 37 additional states have been added. Not all states were territories before they became states, however. Three of the new states were independent sovereign states at the time they were admitted (Vermont, Texas, and California), and three were carved out of existing states (Kentucky, part of Virginia; Maine part of Massachusetts; West Virginia out of Virginia). Hawaii was a sovereign state between 1894 and 1898 before it became a territory. 

Five states were added during the 20th century. The last states to be added to the US were Alaska and Hawaii in 1959. The following table lists each state with the date it entered the union, and its status before they were states.

States and Their Dates of Admission to the Union

  State Status Before Statehood Date Admitted to the Union
1 Delaware Colony Dec. 7, 1787
2 Pennsylvania Colony Dec. 12, 1787
3 New Jersey Colony Dec. 18, 1787
4 Georgia Colony Jan. 2, 1788
5 Connecticut Colony Jan. 9, 1788
6 Massachusetts Colony Feb. 6, 1788
7 Maryland Colony April 28, 1788
8 South Carolina Colony May 23, 1788
9 New Hampshire Colony June 21, 1788
10 Virginia Colony June 25, 1788
11 New York Colony July 26, 1788
12 North Carolina Colony Nov. 21, 1789
13 Rhode Island Colony May 29, 1790
14 Vermont Independent republic, established January 1777 March 4, 1791
15 Kentucky Part of Virginia state June 1,1792
16 Tennessee Territory established May 26, 1790 June 1, 1796
17 Ohio Territory established July 13, 1787 March 1, 1803
18 Louisiana Territory, established July 4, 805 April 30, 1812
19 Indiana Territory established July 4, 1800 Dec.11, 1816
20 Mississippi Territory established April 7, 1798 Dec.10, 1817
21 Illinois Territory established March 1, 1809 Dec.3, 1818
22 Alabama Territory established March 3, 1817 Dec.14, 1819
23 Maine Part of Massachusetts March 15, 1820
24 Missouri Territory established June 4, 1812 Aug. 10, 1821
25 Arkansas Territory established March 2, 1819 June 15, 1836
26 Michigan Territory established June 30, 1805 Jan. 26, 1837
27 Florida Territory established March 30, 1822 March 3, 1845
28 Texas Independent republic, March 2, 1836 Dec.29, 1845
29 Iowa Territory established July 4, 1838 Dec.28, 1846
30 Wisconsin Territory established July 3, 1836 May 26, 1848
31 California Independent republic, June 14, 1846 Sept. 9, 1850
32 Minnesota Territory established March 3, 1849 May 11, 1858
33 Oregon Territory established Aug. 14, 1848 Feb. 14, 1859
34 Kansas Territory established May 30, 1854 Jan. 29, 1861
35 West Virginia Part of Virginia June 20, 1863
36 Nevada Territory established March 2, 1861 October 31, 1864
37 Nebraska Territory established May 30, 1854 March 1, 1867
38 Colorado Territory established Feb. 28, 1861 Aug. 1, 1876
39 North DakotaTT Territory established March 2, 1861 Nov. 2, 1889
40 South Dakota Territory established March 2, 1861 Nov. 2, 1889
41 Montana Territory established May 26, 1864 Nov. 8, 1889
42 Washington Territory established March 2, 1853 Nov. 11, 1889
43 Idaho Territory established March 3, 1863 July 3, 1890
44 Wyoming Territory established July 25, 1868 July 10, 1890
45 Utah Territory established Sep. 9, 1850 Jan. 4, 1896
46 Oklahoma Territory established May 2, 1890 Nov. 16, 1907
47 New Mexico Territory established Sep. 9, 1950 Jan. 6, 1912
48 Arizona Territory established Feb. 24, 1863 Feb. 14, 1912
49 Alaska Territory established Aug. 24, 1912 Jan. 3, 1959
50 Hawaii Territory established Aug. 12, 1898 Aug. 21, 1959

U.S. Territories

There are currently 16 territories owned by the United States, mostly islands in the Pacific ocean or Caribbean Sea, most of which are uninhabited and administered as wildlife refuges by the US Fish and Wildlife Services or as military outposts. United States territories with inhabitants include American Samoa (established 1900), Guam (1898), the 24 Northern Marianas islands (today a commonwealth, established 1944), Puerto Rico (a commonwealth, 1917), U.S. Virgin Islands (1917), and Wake Island (1899).

Sources and Further Reading

  • Biber, Eric, and Thomas B. Colby. "The Admissions Clause." National Constitution Center.
  • Immerwahr, Daniel. "How to Hide an Empire: A History of the Greater United States." New York: Farrar, Straus and Giroux, 2019. 
  • Lawson, Gary, and Guy Seidman. "The Constitution of Empire: Territorial Expansion and American Legal History." New Haven: Yale University Press, 2004. 
  • Mack, Doug. "The Not-Quite States of America: Dispatches from the Territories and Other Far-Flung Outposts of the USA." W. W. Norton, 2017.
  • "The last time Congress created a new state." Constitution Daily. The National Constitution Center, March 12, 2019.