| 1845–1958 | Germany [earth sciences] | German naturalist and explorer Alexander von Humboldt lays the basis of modern geography with the publication of Kosmos/Cosmos, in which he arranges geographic knowledge in a systematic fashion. |
| 1909 | USA [family planning] | The increasing cost of living in the USA is resulting in people having smaller families. |
| 1909 | [fiction] | The French writer André Gide publishes his novel La Porte Etroite/Strait is the Gate. |
| 1909 | Palestine, Ottoman Empire [Judaism] | Russian and Polish Jews set up the first kibbutz, Degania, at Lake Kinnaret, Tiberias, in Palestine. |
| 1909 | [art] | US sociologist Lewis Hein takes Carrying-in Boy, one of the best-known images of a range of his photographs, to highlight the working conditions of the US poor. |
| 1909 | [chemistry] | Danish biochemist Søren Peer Lauritz Sørensen devises the pH scale for measuring acidity and alkalinity. |
| 1909 | USA [cinema and film] | US film director D W Griffith works with Canadian-born child actor Gladys Smith, and helps transform her into Mary Pickford, one of the first great movie stars, who comes to be known as ‘America's Sweetheart’. Their first film together is The Violin Maker of Cremona (1909). |
| 1909 | [civic and commercial buildings] | The School of Art, designed by the Scottish architect Charles Rennie Mackintosh, is completed in Glasgow, Scotland. It is one of the most original art nouveau buildings in Britain. |
| 1909 | [civic and commercial buildings] | The AEG Turbine Factory in Berlin, Germany, designed by the German architect Peter Behrens, is completed. It is one of the first steel and glass buildings. |
| 1909 | [philosophy] | Italian philosopher Benedetto Croce publishes Logica come scienza del concetto puro/Logic as the Science of Pure Concept. |
| 1909 | [philosophy] | US philosopher William James publishes The Meaning of Truth: A Sequel to ‘Pragmatism’. |
| 1909 | [physics] | German-born US physicist Albert Einstein introduces his idea that light exhibits both wave and particle characteristics. |
| 1909 | United Kingdom [shops and shopping] | The first Woolworth's store in Britain is opened in Liverpool. |
| 1909 | [songs] | The English composer Ralph Vaughan Williams completes his song cycle, On Wenlock Edge, inspired by the poems of A E Housman, and his Symphony No. 1, A Sea Symphony. |
| 1909 | [songs] | The Austrian composer Gustav Mahler completes his Song-Symphony Das Lied von der Erde/The Song of the Earth, set to poems translated from Chinese. |
| 1909 | United Kingdom [women's rights] | The suffragette Marion Wallace Dunlop becomes the first hunger striker in Britain: she is released after 91 hours. |
| 1 January 1909 | United Kingdom [welfare] | The first old-age pensions are paid out by the government in Britain.These are noncontributory: the payment is small and made on a restricted basis at the age of 70. |
| 13 February 1909 | Anatolia, Ottoman Empire [administration] | The grand vizier of the Ottoman Empire, Kiamil Pasha, is forced to resign by the Turkish nationalists, who now dominate the Ottoman parliament. |
| March 1909 | USA [cinema and film] | The National Board of Censorship of Motion Pictures is founded in the USA. There is no classification system for films – they are either approved or cuts are recommended. |
| 15 March 1909 | United Kingdom, USA [shops and shopping] | The US businessman H G Selfridge opens the first modern department store in Britain, Selfridge's in London, England, using the slogan, ‘All your shopping under one roof.’ |
| 13 April 1909 | Anatolia, Ottoman Empire [revolution] | An army counter-revolution begins in Constantinople (modern Istanbul), Ottoman Empire, against the rule of the Young Turks, following agitation by the Islamic Mohammedan Union. |
| 27 April 1909 | Anatolia, Ottoman Empire [law and government] | The Young Turks depose the Ottoman sultan Abdul Hamid II because of his sympathy for the attempted counter-revolution. He is succeeded by his brother Mohammed V (–1918). |
| 29 April 1909 | United Kingdom [law and government] | The British chancellor of the Exchequer, David Lloyd George, introduces his ‘People's Budget’, which proposes taxes on land values, profits on land sales, and a ‘super-tax’ on high incomes, in order to raise money for defence and social expenditure. |
| June 1909 | USA [human rights] | The National Association for the Advancement of Colored People (NAACP) is formally established in New York City as the National Committee for the Advancement of the Negro. |
| 14 July 1909 | Germany [law and government] | Bernhard von Bülow resigns as German chancellor because of disagreements with Kaiser Wilhelm II and the naval programme, and is succeeded by Theobald von Bethmann Hollweg. |
| 16 July 1909 | Persia [administration] | Mohammed Ali, shah of Persia, is deposed by the pro-liberal Bakhtiari chief, Ali Kuli Khan, in favour of Sultan Ahmad Shah, aged 12. |
| 25 July 1909 | France, United Kingdom [aircraft] | French aviator Louis Blériot crosses the English Channel by monoplane in 37 minutes from Le Boraques, France, to Dover, England. |
| 30 November 1909 | United Kingdom [law and government] | The hereditary British House of Lords rejects the ‘People's Budget’ by 350 votes to 75, which was passed by the elected House of Commons. The issue generates a major constitutional crisis in Britain. |
| 12 December 1909 | Honduras [wars] | Civil war breaks out in Honduras between the supporters of President Miguel Dávila and ex-president Manuel Bonilla, and continues until 1911. |
| 17 December 1909 | Belgium [political events] | Following the death of King Leopold II of Belgium, Albert I succeeds as king (–1934). |
