1820
March
The Missouri Compromise is negotiated allowing Maine to be admitted to the Union as a free state and Missouri as a slave state in 1821. This act will maintain a balance between free and slave states. The compromise establishes the 36 degree, 30' parallel of latitude as a dividing line between free and slave areas of the territories.
1821
August
Missouri becomes the twenty fourth state and enters the Union as a slave state.
1836
June
Arkansas becomes the twenty fifth state and enters the Union as a as a slave state.
1837
November
Abolitionist publisher Elijah P. Lovejoy is murdered in Alton, Illinois and his printing press is thrown in the river. He had been calling for an end to slavery.
1854
May 30
The Kansas-Nebraska Act passes Congress and thus overturns the Missouri Compromise opening the Northern territory to slavery. Both sides begin to send settlers into the areas in an effort to influence the future status of these areas.
1855
Throughout the year
As Kansas prepares for elections thousands of Border Ruffians from Missouri enter the territory in an effort to influence the election. This begins the Bloody Kansas period with duplicate constitutional conventions, separate elections and constant and violent attacks.
1857
March
Dred Scott Decision - The Supreme Court rules in Scott v. Sandford that blacks are not U.S. citizens, and slaveholders have the right to take existing slaves into free areas of the county.
1858
April 10
Long-time Missouri political titan, Thomas Hart Benton, dies in Washington, D.C. Benton's political career was ended over his refusal to "agitate" over the Slavery question, and his fall from power in the period 1849-1856 presaged the coming war.
1860
August 6
Claiborne Jackson elected governor of Missouri. Thomas C. Reynolds elected Lt. Gov. Both run as "Douglas Democrats" (anti-secession) and not "Breckenridge Democrats" (pro-States Rights).
November
Abraham Lincoln is elected president. Lincoln received 40% of the popular vote and won 59% of the Electoral votes. He was not even on the ballot in the deep south.
1861
January 29
Kansas becomes the thirty fourth state and enters the Union as a free state.
February 2
Captain Nathaniel Lyon arrives for duty at St. Louis Arsenal.
February 13
New state law bans "unauthorized militias" (aimed at Blair's Home Guards). Minute Men organization (approx. 300 men) mustered into Missouri State Guard, forming 5 companies under Captains Barret, Duke, Shaler, Green, and Hubbard.
February 18
Voting for delegates to convention to determine whether Missouri would stay in the Union. No avowed secessionists elected.
March 22
Convention adjourns subject to call of the chair. Final report determines that "That at present there is no adequate cause to impel Missouri to dissolve her connection with the Federal Union."
April 17
Governor Jackson refuses the Federal government Missouri's regiments, saying, "Your requisition, in my judgment, is illegal, unconstitutional, and revolutionary in its objects, inhuman and diabolical, and cannot be complied with."
May 6
Arkansas secedes from the Union.
May 10
Union forces capture Camp Jackson, and a riot follows in St. Louis.
May 12
Governor Jackson appoints ex-Governor --and current president of the State Convention-- Sterling Price as Major General commanding the Missouri State Guard.
June 11
Meeting at the Planter's House in St Louis between USA General Nathanial Lyon and CSA General Sterling Price and Govenor Clairborn Fox Jackson. Lyon declares "This means war. In an hour one of my officers will call for you and conduct you out of my lines."
June 17
Battle of Booneville (Missouri).
July 5
Battle of Carthage (Missouri).
July 26
General John Charles Fremont arrives in St. Louis to take command of Western Department.
August 10
Battle of Wilson's Creek (Missouri). USA General Nathanial Lyon is killed. He is the first Union General killed in action.
August 14
Martial law declared in St. Louis. Maj. McKinstry, then acting Quartermaster, appointed Provost Marshal.
September 13 - 20
Battle of Lexington (Missouri).
September 24
Gen. Samuel R. Curtis assumed command of the city of St. Louis, and vicinity.
November 2
John C. Fremont relieved of command. Maj. Gen. Hunter placed in command.
November 7
Battle of Belmont Missouri. City falls into Union control.
November 9
General Henry W. Halleck takes command of Department of the Missouri. Maj. Gen. Hunter relinquishes command to Halleck Nov. 18, 1861.
November 28
Missouri admitted to Confederacy despite its not having seceded.
December 22
The first prisoners arrive at Gratiot Street Prison. One dies practically on the doorstep as the prisoners wait outside in the cold for entry. There were about 1300 men who arrived in 36 train cars. They were escorted by the 25th Indiana and 2nd Iowa Regiments. Crowds followed the column, occasionally cheering for the prisoners.