- Abraham Lincoln takes office as President of the United States in March.
- Before that, in January and February, Jefferson Davis resigns from the US Senate and many other states secede from the Union and form the Confederate States of America with Davis as its provisional President.
- Colorado and Nevada are organized as US Territories. Washington is still not a state.
- The American Civil War begins with the Battle of Fort Sumter in April. Several other states secede from the Union.
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