The order which the original 13 states ratified the constitution, then the order that the others were admitted to the union
This is a list of U.S. states by date of statehood. It has the date when each U.S. state joined the Union. However,
Virginia's peoples convention in May-June 1776 prepared the first Constittion for a State Government, plus a Declartion of Rights. Other Colonies became States in late 1776 and into 1777, and used Virginia's Declaration of Rights as a pattern for their own Declaration. In the 1778 Articles of Confederation, which formed the first national goverment, it specified the name of the country as "The United States of America", stating "Each State retainms its sovereignity, freedom and independence, and every poeer, jurisdiction, and right, which is not by this Confederation expressly delegated." It also stated "Articles of Confederation and perpetual Union between the States, or a Union of State Legislatures. The first 13 States thus were in this Union from 1778 to 1789, when the second national government was established by a Constitution, which, in list of purposes, "in order to form a more perfect Union". This does not make the States enter the Union only when it ratified the U.S. Constitution. The 1787 Convention, which decided not to amend the Articles for the first national government but prepare a Constitution, selected.the Virginia Plan of a three-branch, republikcan form of government, and went one step further and had the Constitution guarantee the same form of government in each State. The Constitution does not use the word "Democracy" nor "Republic", and the founders/framers provided the prerequisites and other elements of the unique republican form of government.
*Congress extended federal laws to Ohio on February 19, 1803, but no formal date of statehood was set by the act of admission or a later resolution, as occurred with all other new states. On August 7, 1953, Congress passed a law retroactively making Ohio a state as of March 1, 1803, the date when Ohio's first legislature convened.
† The actual statehood proclamations for North and South Dakota were intentionally shuffled so that no one actually knows which was admitted first. However, North Dakota's was published first in the Statutes at Large (since it is first in the alphabet); hence, it is considered admitted first by most sources (including the 50 State Quarters program).