| 1800–1850 | USA [consumer products] | A revolution in retail and wholesale trade occurs: specialization transforms the urban retail market, replacing the general store with individual stores for hardware, groceries, dry goods, furnishing, books, tobacco, and so on. Cash-only sales policies are instituted around 1806. |
| 1810–1859 | USA [agriculture] | US cotton production, the vast majority of which is grown in the southern states, rises from 171,000 bales in 1810 to just under 5.4 million in 1859. |
| 1840–1850 | USA [farming] | Wheat becomes an increasingly important cash crop in the USA; production in 1839 is nearly 85 million bushels and climbs to over 100 million bushels in 10 years. |
| 1840–1860 | world [plagues and epidemics] | A cholera pandemic kills millions of people worldwide. |
| 1841–1850 | USA, UK [statistics and demography] | Emigration to the USA is 267,044 from Britain and 780,719 from Ireland. |
| 1842–1845 | UK [astronomy] | Irish astronomer William Parsons (later Lord Rosse) builds the 180 cm/72 in reflecting telescope ‘Leviathan’. |
| 1843 | Scotland, England [historical study] | The Scottish essayist and social historian Thomas Carlyle publishes Past and Present, in which he compares life in the Middle Ages to life in Victorian England. |
| 1843 | UK [computing] | English mathematician Ada Byron, Countess Lovelace, writes a programme for Charles Babbage's analytical engine – the first computer programme. |
| 1843 | UK [rugby] | Guy's Hospital Rugby Football Club, the world's oldest rugby club still in existence, is founded in London, England. |
| 1843 | UK [newspapers] | The News of the World, a new Sunday newspaper, is launched in London, England. Its immediate popularity means that it is soon the best-selling paper in the world. |
| 1843 | Germany, UK, USA [opera] | The opera Die fliegende Holländer/Flying Dutchman by the German composer Richard Wagner is first performed, in Dresden, Germany. It is first performed in Britain in 1870 (in London, England), and in the USA in 1876 (in Philadelphia, Pennsylvania). |
| 1843 | England [philosophy] | The English philosopher John Stuart Mill publishes The System of Logic. |
| 1843 | Denmark [philosophy] | The Danish philosopher Søren Aabye Kierkegaard publishes Enten-Eller/Either/Or, his first major philosophical work, and Frygt og baeven/Fear and Trembling. His analysis of choice makes this work one of the early classics of existentialism. |
| 1843 | England [physics] | English physicist James Joule determines the value for the mechanical equivalent of heat (now known as the joule), that is the amount of work required to produce a unit of heat. |
| 11 April 1843 | Gambia, Sierra Leone, UK [law and government] | A British act of Parliament separates Gambia from Sierra Leone, west Africa, as a crown colony. |
| 15 April 1843 | USA, UK [births and deaths] | Henry James, US-born British novelist and playwright, born in New York City (–1916). |
| 4 May 1843 | Natal, UK [colonization] | Natal in southern Africa is proclaimed a British colony. |
| 19 July 1843 | England [ships and shipping] | English engineer Isambard Kingdom Brunel's ship Great Britain is launched at Bristol, England. It is the world's largest ship (98 m/322ft long; weighing 3,332 tonnes/3,270 tons), with six masts and a screw propeller, and becomes the first propeller-driven iron ship to cross the Atlantic. It sets a pattern for ocean liners for the rest of the century. |
| 8 August 1843 | India, UK [colonization] | Britain formally annexes the Indian province of Sind (in modern-day Pakistan), having militarily subdued its inhabitants. |
| 19 September 1843 | France [births and deaths] | Gustave-Gaspard Coriolis, French engineer who was the first to describe the Coriolis force, dies in Paris, France (50). |
