- Oct 2 Former US VP John C Breckinridge flees Kentucky
- Oct 6 Naval Engagement at Charleston, South Carolina, USS Flag vs BR Alert
- Oct 6 Revolt of Russian student shuts down university of Petersburg
- Oct 11 Battle of Dumfries, VA (Quantico Creek)
- Oct 12 Confederate ironclad Manassas attack Union's Richmond on Mississippi
- Oct 16 Confederacy starts selling postage stamps
- Oct 21 Battle of Balls Bluff, VA (Leesburg, Harrison's Island)
- Oct 22 1st telegraph line linking West & East coasts completed
- Oct 24 First US transcontinental telegram is sent (from San Francisco to Washington, D.C.)
- Oct 24 West Virginia secedes from Virginia
- Oct 25 First Battle of Springfield [Zagonyi's Charge], fought in Springfield, Missouri, Union victory (US Civil War)
- Oct 25 Telegraph message sent from St Louis to San Francisco
- Oct 25 Toronto Stock Exchange created
Pony Express Ends
Oct 26 Pony Express (Missouri to California) ends after 19 months
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