December 20, 1860
- South Carolina becomes the first state to attempt to secede from the United States.
- Governor Francis W. Pickens takes office in South Carolina.
- Governor Francis Pickens of South Carolina demands President Buchanan relinquish control of Fort Sumter and Fort Moultrie.
- Edwin Stanton becomes Attorney-General in the Buchanan Administration
- Secretary of War John Floyd orders 113 columbiad cannon and 11 32-pounders from the Pittsburgh arsenal to Ship Island, Mississippi, and Galveston.