May 19, 1900 (Saturday)
- A day after signing a treaty with King Taufa'ahau Tupou II of Tonga, emissary Basil Thomson declared the South Pacific kingdom to be a protectorate of the United Kingdom. Thomson had spent six weeks in trying to persuade the reluctant King to accept British protection, before threatening to depose the monarch as a last option.
- The Convention for the Preservation of Wild Animals, Birds and Fish in Africa was signed in London by representatives of the European colonial powers, marking the first international agreement to protect wildlife.
- Mining prospector Jim Butler was returning to his home in Belmont, Nevada, when he and his burro stopped to dig at a high canyon near Tonopah. There, he discovered a large outcropping of silver and went from poverty to wealth, while his find set off a mining boom.
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