Events from the year 1789 in the United States. The Articles of Confederation, the agreement under which the nation's government had been operating since 1781, was superseded by the Constitution in March of this year.
April 6 – At Federal Hall, the United States Senate attains its first quorum and elects Senator John Langdon as its first president pro tempore; the first joint session of Congress is held on that same date, and the electoral votes of the first presidential election are formally counted. General George Washington is declared President-elect, and John Adams is declared Vice President-elect.
April 21
John Adams takes office as Vice-President of the United States and begins to preside the sessions of the United States Senate.
September 25 – The United States Congress proposes a set of 12 amendments for ratification by the states. Ratification for 10 of these proposals is completed on December 15, 1791, creating the United States Bill of Rights.
September 29 – The U.S. Department of War establishes the nation's first regular army, with a strength of several hundred men.
Influenced by Dr. Benjamin Rush's argument against the excessive use of alcohol, about 200 farmers in a Connecticut community form a temperance association.
December 17 – Clement Comer Clay, U.S. Senator from Alabama from 1837 to 1841 (died 1866)
December 21 – John Norvell, U.S. Senator from Michigan from 1837 to 1841 (died 1850)
December 22 – Levi Woodbury, U.S. Senator from New Hampshire from 1825 to 1831 & 1841 to 1845, 9th Governor of New Hampshire from 1823 to 1824, 13th U.S. Secretary of the Treasury from 1834 to 1841, and Associate Justice of the Supreme Court of the U.S. from 1845 (died 1851)
November 10 – Richard Caswell, major general of the Revolutionary War, Continental Congressman and Governor of North Carolina from 1776 to 1780 & 1785 to 1787) (born 1729)
November 17 – Samuel Holden Parsons, major general of the Revolutionary War, member of the Connecticut House of Representatives (born 1737)
December 10 – William Pierce, member of the Georgia House of Representatives, Continental Congressman for Georgia (born 1753)