This is a list of U.S. states by date of statehood, that is, the date when each U.S. state joined the Union. Although the first 13 states can be considered to have been members of the United States from the date of the Declaration of Independence – July 4, 1776 – or from the date on which they ratified the Articles of Confederation, they are presented here as being "admitted" on the date each ratified the present United States Constitution; most other such lists, including the 50 State Quarters program, do the same.

The admission dates for later states were set by either the act of admission or a later resolution issued under that act, except for Ohio, whose date of admission was determined by act of Congress in 1953 as March 1, 1803 when its legislature first met because of a clerical error of omission — the original act omitted setting a date that the act took effect.

This list does not account for the secession of 11 states during the American Civil War to form the Confederate States of America, the subsequent restoration of those states to representation in Congress (sometimes called "readmission") between 1866 and 1870, or the end of Reconstruction in those states; since their secession was declared illegal by the Supreme Court in Texas v. White, they never legally left the Union. It also does not account for secessionist governments formed in two other states, as their Unionist governments generally remained in control.

A U.S. state is a federated state of the United States of America that shares sovereignty with the United States federal government. Since the admission of Hawaii as a state in August 1959, there are fifty U.S. states. Because of the shared sovereignty between a U.S. state and the U.S. federal government, an American is a citizen of both the federal entity and of his or her state of domicile. Kentucky, Massachusetts, Pennsylvania, and Virginia use the official title of Commonwealth rather than State. State citizenship is flexible and no government approval is required to move between states, with the exception of paroled convicts.

The United States Constitution allocates certain powers to the federal government. It also places some limitations on the state governments. State governments are allocated power by the people (of each respective state) through their individual constitutions. By ratifying the United States Constitution, the people transferred certain limited sovereign powers to the federal government from their states. Under the Tenth Amendment, all powers not delegated to the federal government nor prohibited to the states are retained by the states or the people. Historically, the tasks of public safety (in the sense of controlling crime), public education, public health, transportation, and infrastructure have generally been considered primarily state responsibilities, although all of these now have significant federal funding and regulation as well (based largely upon the Commerce Clause, the Taxing and Spending Clause, and the Necessary and Proper Clause of the Constitution).

George Washington (February 22, 1732 [O.S. February 11, 1731] – December 14, 1799) was the first President of the United States of America, serving from 1789 to 1797, and the dominant military and political leader of the United States from 1775 to 1799. He led the American victory over Great Britain in the American Revolutionary War as commander-in-chief of the Continental Army from 1775 to 1783, and presided over the writing of the Constitution in 1787. Washington became the first president, by unanimous choice, and oversaw the creation of a strong, well-financed national government that maintained neutrality in the wars raging in Europe, suppressed rebellion, and won acceptance among Americans of all types. His leadership style established many forms and rituals of government that have been used since, such as using a cabinet system and delivering an inaugural address. Washington is universally regarded as the "Father of his country."

Barack Hussein Obama II (ⁱ/bəˈrɑːk huːˈseɪn oʊˈbɑːmə/; born August 4, 1961) is the 44th and current President of the United States. He is the first African American to hold the office. In January 2005, Obama was sworn in as a U.S. Senator in the state of Illinois. He would hold this office until November 2008, when he resigned following his victory in the 2008 presidential election.

Born in Honolulu, Hawaii, Obama is a graduate of Columbia University and Harvard Law School, where he was the president of the Harvard Law Review. He was a community organizer in Chicago before earning his law degree. He worked as a civil rights attorney in Chicago and taught constitutional law at the University of Chicago Law School from 1992 to 2004. He served three terms representing the 13th District in the Illinois Senate from 1997 to 2004.

Following an unsuccessful bid against the Democratic incumbent for a seat in the United States House of Representatives in 2000, Obama ran for the United States Senate in 2004. Several events brought him to national attention during the campaign, including his victory in the March 2004 Illinois Democratic primary for the Senate election and his keynote address at the Democratic National Convention in July 2004. He won election to the U.S. Senate in Illinois in November 2004. His presidential campaign began in February 2007, and after a close campaign in the 2008 Democratic Party presidential primaries against Hillary Rodham Clinton, he won his party's nomination. In the 2008 presidential election, he defeated Republican nominee John McCain, and was inaugurated as president on January 20, 2009. Nine months later, Obama was named the 2009 Nobel Peace Prize laureate. In April 2011, he announced that he would be running for re-election in 2012.