- Jan 17 A group of Modoc warriors defeats the United States Army in the First Battle of the Stronghold, a part of the Modoc War.
- Feb 20 British Naval Officer John Moresby discovers the site of Port Moresby, Papua New Guinea and claims it for Britain
- May 27 Heinrich Schliemann discovers "Priam's Treasure" a cache of gold and other objects in Hisarlik (Troy) in Anatolia
- Jun 5 Sultan Bargash bin Said under British pressure closes the infamous slave market of Zanzibar in modern day Tanzania
- Sep 18 Government bond agent Jay Cooke & Co collapses, causing panic on Wall St, the start of the panic of 1873 and the Long depression
- May 23 1st Preakness Stakes: G. Barbee aboard Survivor wins in 2:43 at Pimlico Race Course, Baltimore, Maryland
US Congress enacts the Comstock Law, making it illegal to send any "obscene, lewd, or lascivious" books through the mail
On March 3, 1873