|Centuries:||17th century – 18th century – 19th century|
|Decades:||1760s 1770s 1780s – 1790s – 1800s 1810s 1820s|
|Years:||1788 1789 1790 – 1791 – 1792 1793 1794|
|1791 by topic:|
|Arts and Sciences|
|Archaeology – Architecture – Art – Literature (Poetry) – Music – Science|
|Australia – Austria – Canada –Denmark – France – Great Britain – Ireland – Norway – Portugal – Russia – Scotland –Sweden – United States|
|Lists of leaders|
|Colonial governors – State leaders|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Ab urbe condita||2544|
|British Regnal year||31 Geo. 3 – 32 Geo. 3|
|Chinese calendar||庚戌年 (Metal Dog)
4487 or 4427
— to —
辛亥年 (Metal Pig)
4488 or 4428
|- Vikram Samvat||1847–1848|
|- Shaka Samvat||1712–1713|
|- Kali Yuga||4891–4892|
|Japanese calendar||Kansei 3
|Julian calendar||Gregorian minus 11 days|
|Minguo calendar||121 before ROC
|Thai solar calendar||2333–2334|
|Wikimedia Commons has media related to 1791.|
1791 (MDCCXCI) was a common year starting on Saturday (dominical letter B) of the Gregorian calendar and a common year starting on Wednesday (dominical letter E) of the Julian calendar, the 1791st year of the Common Era (CE) and Anno Domini (AD) designations, the 791st year of the 2nd millennium, the 91st year of the 18th century, and the 2nd year of the 1790s decade. As of the start of 1791, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1918.
- January 12 – Holy Roman troops reenter Liège, heralding the end of the Liège Revolution and the restoration of its Prince-Bishops.
- January 25 – The British Parliament passes the Constitutional Act 1791, splitting the old province of Quebec into Upper and Lower Canada.
- February 21 – The United States opens diplomatic relations with Portugal.
- March 2 – In France:
- March 4 – Vermont is admitted as the 14th U.S. state.
- March 13 – Thomas Paine's chief work Rights of Man (first part) is published in London.
- March – In France, the National Constituent Assembly accepts the recommendation of its Commission of Weights and Measures that the nation should adopt the metric system.
- April 21 – The first of forty boundary stones delineating the borders of the new District of Columbia in the United States is laid at Jones Point Light, in Alexandria, Virginia.
- May 3 – The Sejm of the Polish–Lithuanian Commonwealth proclaims the Constitution of May 3, 1791, the first modern codified constitution in Europe.
- June 20 – Flight to Varennes: The French Royal Family is captured when they try to flee in disguise.
- June 21 – Foundation date of the Ordnance Survey in Great Britain.
- July 8 – Composer Joseph Haydn is awarded an honorary doctorate of music at the University of Oxford.
- July 14 – The Priestley Riots against Dissenters break out in Birmingham, England.
- July 17 – The Champ de Mars Massacre occurs during the French Revolution.
- August 4 – The Treaty of Sistova is signed, ending the Ottoman–Habsburg wars.
- August 6 – The Brandenburg Gate in Berlin is finished.
- August 21 – Haitian Revolution: A slave rebellion breaks out in the French colony of Saint-Domingue.
- August 26 – John Fitch is granted a patent for the steamboat in the United States.
- August 27 – Battle of Tellicherry (Third Anglo-Mysore War) off the south-west coast of India: a British Royal Navy patrol forces a French convoy bound for Mysore to surrender.
- September 6 – Wolfgang Amadeus Mozart's opera seria La clemenza di Tito premières at the Estates Theatre in Prague to mark the coronation of Leopold II as King of Bohemia.
- September 13 – Louis XVI of France accepts the final version of the completed constitution.
- September 25 – Mission Santa Cruz is founded by Father Fermín Lasuén, becoming the 12th mission in the California mission chain.
- September 28 – Promulgation of the law on Jewish emancipation in France, the first such legislation in modern Europe.
- September 30 – Wolfgang Amadeus Mozart's singspiel opera The Magic Flute (Die Zauberflöte) premières at the Freihaus-Theater auf der Wieden in Vienna.
- October – The Legislative Assembly (France) convenes.
- October 9 – Mission Nuestra Señora de la Soledad is founded by Father Fermín Lasuén, becoming the 13th mission in the California mission chain.
- October 28 – Publication of the Declaration of the Rights of Woman and the Female Citizen in France.
- December 4 – The first issue of The Observer, the world's first Sunday newspaper, is published in London.
- December 5 – Austrian composer Wolfgang Amadeus Mozart dies aged 35 at his home in Vienna, perhaps of acute rheumatic fever, and is buried two days later.
- December 15 – Ratification by the states of the first ten amendments to the United States Constitution is completed, creating the United States Bill of Rights. Two additional amendments remain pending, and one of these is finally ratified in 1992, becoming the Twenty-seventh Amendment.
- The first American ship reaches Japan.
- An ordinance is written barring the game of baseball within 80 yards of the Meeting House in Pittsfield, Massachusetts (first known reference to the game of baseball in North America).
- The School for the Indigent Blind, the oldest continuously operating specialist school of its kind in the world, is founded in Liverpool, England, by blind ex-merchant seaman, writer and abolitionist Edward Rushton.
- The Casbah of Algiers Palace is completed.
- January 15 – Franz Grillparzer, Austrian writer (d. 1872)
- January 28 – Ferdinand Hérold, French composer (d. 1833)
- February 12 – Peter Cooper, American industrialist, inventor and philanthropist (d. 1883)
- February 21
- April 23 – James Buchanan, 15th President of the United States (d. 1868)
- April 27 – Samuel Morse, American inventor (d. 1872)
- June 30 – Félix Savart, French physicist (d. 1841)
- July 26 – Franz Xaver Wolfgang Mozart, Austrian composer and pianist (d. 1844)
- September 5 – Giacomo Meyerbeer, German composer (d. 1864)
- September 21 – István Széchenyi, Hungarian politician and writer (d. 1860)
- September 22 – Michael Faraday, British scientist (d. 1867)
- September 23 – Theodor Körner, German author and soldier (d. 1813)
- September 26 – Théodore Géricault, French painter (d. 1824)
- October 29 – John Elliotson, British physician (d. 1868)
- November 11 – Josef Munzinger, member of the Swiss Federal Council (d. 1855)
- December 7 – Ferenc Novák Hungarian Slovene writer (d. 1836)
- December 26 – Charles Babbage, British mathematician and inventor (d. 1871)
- date unknown – Enriqueta Favez, Swiss physician and surgeon (d. 1856)
- January 11 – William Williams Pantycelyn, Welsh hymnist (b. 1717)
- March 2 – John Wesley, English founder of Methodism (b. 1703)
- March 14 – Johann Salomo Semler, German historian and Bible commentator (b. 1725)
- April 2 – Honoré Gabriel Riqueti, comte de Mirabeau, French revolutionary leader (b. 1749)
- April 19 – Richard Price, Welsh philosopher (b. 1723)
- May 9 – Francis Hopkinson, American signer of the Declaration of Independence (b. 1737)
- June 5 – Frederick Haldimand, Swiss-born British colonial governor (b. 1718)
- June 10 – Toussaint-Guillaume Picquet de la Motte, French admiral (b. 1720)
- July 17 – Martin Dobrizhoffer, Austrian Jesuit missionary (b. 1717)
- July 25 – Isaac Low, American delegate to the Continental Congress (b. 1735)
- August 16 – Charles-François de Broglie, marquis de Ruffec, French soldier and diplomat (b. 1719)
- September 25 – William Bradford, American printer (b. 1719)
- November 4 – Richard Butler, American soldier (b. 1743)
- December 5 – Wolfgang Amadeus Mozart, Austrian composer (b. 1756)
- December 12 – Etteilla, French occult cartomancer (b. 1738)
- Date unknown – Maria Petraccini, Italian anatomist and physician (b. 1759)
- The Hutchinson Factfinder. Helicon. 1999. ISBN 1-85986-000-1.
- "A short history of the Ordnance Survey of Great Britain" (PDF).
- "Interior of Governors Palace, Algiers, Algeria". World Digital Library. 1899. Retrieved 2013-09-25.