21st century

====2004====
* [[March 11]] – [[2004 Madrid train bombings|Ten explosions occur]] at the [[Cercanías Madrid|Cercanías]] commuter train system of [[Madrid]], [[Spain]], killing 191 people and injuring around 2,000.
* [[May 1]] – The [[European Union]] [[2004 enlargement of the European Union|expands]] by 10 countries (including eight former communist countries, plus [[Malta]] and [[Cyprus]]).
* [[June 5]] – Former U.S. president [[Ronald Reagan]] [[Death and state funeral of Ronald Reagan|dies]] at the age of 93, after suffering nearly a decade from [[Alzheimer's disease]].
* [[September 1]] – A group of Chechen rebels [[Beslan school siege|invade a school in Beslan]], keeping thousands of hostages during three days. A series of shootings and bombings kills 334 people and injured 750.
* [[November 11]] – [[Palestinian people|Palestinian]] leader and Chairman of the [[Palestine Liberation Organization]] [[Yasser Arafat]] dies in France, at the age of 75, from hemorrhagic stroke.
* [[November 18]] – [[Massachusetts]] becomes the first [[U.S. state]] to [[Goodridge v. Department of Public Health|legalize]] [[same-sex marriage]].
* [[December 26]] – [[2004 Indian Ocean earthquake and tsunami]] leaves 227,898 dead.