1861 in the United States

Federal government

• President:

James Buchanan (D-Pennsylvania) (until March 4)

Abraham Lincoln (R-Illinois) (starting March 4)

• Vice President:

John C. Breckinridge (D-Kentucky) (until March 4)

Hannibal Hamlin (R-Maine) (starting March 4)

• Chief Justice: Roger B. Taney (Maryland)
• Speaker of the House of Representatives:

William Pennington (R-New Jersey) (until March 4)

Galusha A. Grow (R-Pennsylvania) (starting July 4)

• Congress: 36th (until March 4), 37th (starting March 4)

January–March

• January 3 – American Civil War: Delaware votes not to secede from the Union.
• January 9 – Mississippi becomes the second state to secede from the Union, preceding the American Civil War.
• January 10 – American Civil War: Florida secedes from the Union.
• January 11 – American Civil War: Alabama secedes from the Union.
• January 12 – Major Robert Anderson sends dispatches to Washington.^{[clarification needed]}
• January 12 – American Civil War: Florida state troops demand surrender of Fort Pickens.^[1]
• January 18 – American Civil War: Georgia secedes from the Union.
• January 21 – American Civil War: Jefferson Davis resigns from the United States Senate. Ordinance of Secession is ratified.
• January 26 – American Civil War: Louisiana secedes from the Union.
• January 29 – Kansas is admitted as the 34th U.S. state (see History of Kansas).
• February 1 – American Civil War: Texas secedes from the Union.
• February 4 – American Civil War: Delegates from six seceded states meet at the Montgomery Convention in Montgomery, Alabama.
• February 8 – American Civil War: The Confederate States of America adopts the Provisional Constitution of the Confederate States.
• February 9 – American Civil War: Jefferson Davis is elected the provisional president of the Confederate States of America by the Weed Convention at Montgomery, Alabama.
• February 11 – American Civil War: The U.S. House unanimously passes a resolution guaranteeing non-interference with slavery in any state.
• February 18 – American Civil War: In Montgomery, Alabama, Jefferson Davis is inaugurated as the provisional president of the Confederate States of America.
• February 23 – President-elect Abraham Lincoln arrives secretly in Washington, D.C., after an assassination attempt in Baltimore.
• February 28 – Colorado Territory is organized.
• March 2 – Nevada Territory and Dakota Territory are organized.
• March 4
  • Abraham Lincoln is sworn in as the 16th president of the United States, and Hannibal Hamlin is sworn in as the 15th vice president.
  • American Civil War: The Stars and Bars is adopted as the flag of the Confederate States of America.
• March 11 – American Civil War: The Constitution of the Confederate States is adopted.

April–June

• April 12 – Battle of Fort Sumter: The American Civil War begins at Fort Sumter, South Carolina.
• April 14 – Battle of Fort Sumter: Fort Sumter surrenders to Confederate forces.
• April 17 – The state of Virginia secedes from the Union.
• April 20 – American Civil War: Robert E. Lee resigns his commission in the United States Army in order to command the forces of the state of Virginia.
• April 25 – American Civil War: The Union Army arrives in Washington, D.C.
• April 27 – American Civil War:
  • President Abraham Lincoln suspends the writ of habeas corpus in Maryland.
• May 6 – American Civil War: Arkansas secedes from the Union.
• May 7 – American Civil War: Tennessee secedes from the Union.
• May 8 – American Civil War: Richmond, Virginia, is named the capital of the Confederate States of America.
• May 10 – American Civil War – Camp Jackson Affair: Union military forces clash with civilians on the streets of St. Louis, Missouri, resulting in the deaths of at least 28 people and injuries to another 100.
• May 13 – American Civil War: Queen Victoria issues a "proclamation of neutrality" which recognizes the breakaway states as having belligerent rights.
• May 20
  • American Civil War: Kentucky proclaims its neutrality which lasts until September 3, when Confederate forces enter the state.
  • American Civil War: North Carolina secedes from the Union.

July–September

• July 13 – American Civil War: The Battle of Corrick's Ford takes place in western Virginia.
• July 21 – American Civil War – First Battle of Bull Run aka First Manassas: at Manassas Junction, Virginia, the first major battle of the war ends in a Confederate victory.
• July 22 – American Civil War: After Union forces led by Nathaniel Lyon capture the Missouri state capital of Jefferson City, the Missouri Constitutional Convention reconvenes and removes pro-secessionist Governor Claiborne Fox Jackson from office, replacing him with a pro-Union governor.
• July 25 – American Civil War: The Crittenden–Johnson Resolution is passed by the U.S. Congress, stating that the war is being fought to preserve the Union and not to end slavery.
• July 26 – American Civil War: George B. McClellan assumes command of the Army of the Potomac following a disastrous Union defeat at the First Battle of Bull Run.
• August 5
  • 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).
  • The U.S. Army abolishes flogging.
  • John Gill Shorter is elected the 17th governor of Alabama defeating Thomas H. Watts.
• August 10 – American Civil War: The first major battle west of the Mississippi River, the Battle of Wilson's Creek, is fought, with a Confederate victory.
• September 3 – American Civil War: Confederate General Leonidas Polk invades neutral Kentucky, prompting the state legislature to ask for Union assistance.
• September 6 – American Civil War: Forces under Union General Ulysses S. Grant bloodlessly capture Paducah, Kentucky, which gives the Union control the mouth of the Tennessee River.

October–December

• October 9 – American Civil War – Battle of Santa Rosa Island: Confederate forces are defeated in their effort to take the island.
• October 21 – American Civil War – Battle of Ball's Bluff: Union forces under Colonel Edward Baker are defeated by Confederate troops in the second major battle of the war. Baker, a close friend of Abraham Lincoln, is killed in the fighting.
• 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.
  • American Civil War: Citing failing health, Union General Winfield Scott resigns as Commander of the United States Army.
• November 1 – American Civil War: U.S. President Abraham Lincoln appoints George B. McClellan as commander of the Union Army, replacing the aged General Winfield Scott.
• November 2 – American Civil War: Western Department Union General John C. Frémont is relieved of command and replaced by David Hunter.
• November 6 – American Civil War: Jefferson Davis is elected president of the Confederate States of America.
• November 7 – American Civil War – Battle of Belmont: In Mississippi County, Union forces led by General Ulysses S. Grant overrun a Confederate camp but are forced to retreat when Confederate reinforcements arrive.
• November 8 – American Civil War – Trent Affair: The USS San Jacinto stops the United Kingdom mail ship Trent and arrests two Confederate envoys, James Mason and John Slidell, sparking a diplomatic crisis between the U.K. and U.S.
• November 21 – American Civil War: Confederate President Jefferson Davis appoints Judah Benjamin Secretary of War.
• November 28 – American Civil War: Acting on the ordinance passed by the Jackson government, the Confederate Congress admits Missouri as the 12th Confederate state.
• December 2 – John Gill Shorter is sworn in as the 17th governor of Alabama replacing Andrew B. Moore.^[2]
• December 10 – American Civil War: Kentucky is accepted into the Confederate States of America.

Ongoing

• Secession crisis (1860–1861)
• American Civil War (1861–1865)

Undated

• Alonzo E. Deitz founds the A. E. Deitz lock company in Brooklyn, New York.