Editing 1804 (section)

=== July–September ===
* [[July 11]] – [[Aaron Burr]], Vice President of the United States, shoots former U.S. Secretary of the Treasury [[Alexander Hamilton]] during a [[Burr–Hamilton duel|duel]]; Hamilton dies the next day.
* [[July 27]] – The [[Twelfth Amendment to the United States Constitution|Twelfth Amendment to the U.S. Constitution]], which reforms the way that candidates for [[President of the United States|President]] and [[Vice President of the United States|Vice President]] are chosen, is ratified by [[Tennessee]], removing doubt surrounding adoption.
* [[August 11]] – In reaction to Napoleon being proclaimed emperor of France, [[Francis II, Holy Roman Emperor|Francis II]] assumes the title of a hereditary emperor of Austria (as Francis I) in addition to his title as emperor of the Holy Roman Empire. This latter title will become obsolete two years later when the formation of the Confederation of the Rhine instigated by Napoleon signals the end of the Holy Roman Empire.
* [[August 20]] – [[Lewis and Clark Expedition]]: The ''[[Corps of Discovery]]'', whose purpose is to explore the [[Louisiana Purchase]], suffers its only death when Sergeant [[Charles Floyd (explorer)|Charles Floyd]] dies, apparently from acute [[appendicitis]].
* [[September 1]] – German astronomer [[Karl Ludwig Harding|K. L. Harding]] discovers the [[asteroid]] [[3 Juno|Juno]].