| 3 | 1801 | - 1801: Grand Union Canal opens in England
- 1801: Elgin Marbles brought from Athens to London
- 1 Jan 1801: Union Jack becomes the official British flag
- 4 Mar 1801—3 Mar 1809: Thomas Jefferson, 3rd President of the United States
 Thomas Jefferson
- 10 Mar 1801: First census puts the population of England and Wales at 9,168,000. Population of Britain nearly 11 million (75% rural)
- 17 Mar 1801—10 May 1804: Henry Addington, 1st Viscount Sidmouth, UK Prime Minister (Tory)
 Viscount Sidmouth
- 1 Apr 1801: First Barbary War
- 24 Dec 1801: Richard Trevithick built the first self-propelled passenger carrying road loco
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