Events from the year 1788 in the United States.

• President: Cyrus Griffin (starting January 29)
• Congress of the Confederation

• January 2 – Georgia ratifies the United States Constitution and becomes the 4th U.S. state under the new government (see History of Georgia).
• January 9 – Connecticut ratifies the United States Constitution and becomes the 5th U.S. state (see History of Connecticut).
• January 22 – the Continental Congress, effectively a caretaker government, elects Cyrus Griffin as its last president.
• February 1 – Isaac Briggs and William Longstreet patent the steamboat in Georgia.
• February 6 – Massachusetts ratifies the United States Constitution and becomes the 6th U.S. state (see History of Massachusetts).
• March 21 – Great New Orleans Fire (1788) kills 25% of the population and destroys 856 buildings, including St. Louis Cathedral and the Cabildo, leaving most of the town in ruins. At the time New Orleans was a Spanish colony that would be secretly given to France in 1800. Not until 1803 would New Orleans as part of the Louisiana Purchase become part of the United States.
• April 7 – American pioneers establish the town of Marietta (in modern-day Ohio), the first permanent American settlement outside the original Thirteen Colonies.
• April 13 – A riot, the Doctors' Mob, begins. Residents of Manhattan are angry about grave robbers stealing bodies for doctors to dissect. The rioting is suppressed on the 15th.
• April 28 – Maryland ratifies the United States Constitution and becomes the 7th U.S. state (see History of Maryland).
• May 23 – South Carolina ratifies the United States Constitution and becomes the 8th U.S. state (see History of South Carolina).
• June 21 – New Hampshire ratifies the United States Constitution and becomes the 9th U.S. state (see History of New Hampshire), the Constitution goes into effect.
• June 25 – Virginia ratifies the United States Constitution and becomes the 10th U.S. state under the new government (see History of Virginia).
• July 26 – New York ratifies the United States Constitution and becomes the 11th U.S. state (see History of New York).
• November 15 – Cyrus Griffin resigns as President of the Continental Congress after only two delegates arrived for the final session.

• Articles of Confederation in effect (1781–1788)
• Northwest Indian War (1785–1795)

• April 14 – David Gouverneur Burnet, politician (died 1870)
• September 15 – Gerard Brandon, 4th and 6th Governor of Mississippi from 1825 till 1826 and from 1826 till 1832. (died 1850)
• September 21 – Margaret Taylor, First Lady of the United States (died 1852)
• November 8 – Jabez W. Huntington, United States Senator from Connecticut from 1840 till 1847. (died 1847)
• Date unknown – Sacagawea, interpreter and guide on the Lewis and Clark Expedition (died 1812)

• January 9 – Benedict Swingate Calvert, judge (born 1722)
• February 28 – Thomas Cushing, 1st Lieutenant Governor of Massachusetts (born 1725)
• March 29 – Charles Wesley (born 1707)

• Timeline of the American Revolution (1760–1789)

• Media related to 1788 in the United States at Wikimedia Commons