American Civil War: In order to help pay for the war effort, the United States government issues the first income tax as part of the Revenue Act of 1861 (3% of all incomes over US$800; rescinded in 1872).
October 28 – A small pro-secessionist section of the Missouri legislature takes up a bill for Missouri's secession from the Union.
October 30 – The bill is passed for Missouri's secession from the Union.
October 31
Missouri's secession from the Union bill is signed by Governor Claiborne Fox Jackson, but by this date Governor Jackson only controls parts of South-Western Missouri. Union forces led by general John C. Frémont have consolidated control over the vast majority of Missouri.
November 28 – American Civil War: Acting on the ordinance passed by the Jackson government, the Confederate Congress admits Missouri as the 12th Confederate state.
November 26 – Albert B. Fall, U.S. Senator from New Mexico from 1912 to 1921 and Secretary of the Interior from 1921 to 1923 under President Warren G. Harding (died 1944)