Northwest Ordinance:
On July 13, 1787, the Confederation Congress passed the Northwest Ordinance, which created a territorial government in the Northwest Territory and a system of establishing new states from it (Ohio, Indiana, Illinois, Michigan, and Wisconsin).  Article 6 banned slavery or involuntary servitude in the Northwest Territory, except as punishment for crime.  It mandated the return of fugitive slaves.  The Northwest Ordinance was one of the last acts of Congress under the Articles of Confederation, which would soon be replaced by the U.S. Constitution.

United States Constitution:
On September 17, 1787, delegates to the Constitutional Convention signed the proposed constitution and sent it to the states for ratification.  On June 21, 1788, the Constitution met the ratification requirement of approval by three-quarters of the states.  The first congressional and presidential elections under the new constitution were held that fall.  The inauguration of George Washington as president and the swearing in of members of the First Congress occurred on March 4, 1789.   

In order to avoid controversy between the North and South, the institution of slavery was not directly mentioned in the text of the original Constitution.  However, the document allowed 3/5 of the number of slaves in a state to count toward that state’s population for purposes of taxation and representation in the U.S. House.  It prohibited Congress from outlawing the importation of slaves from abroad until 1808 (at which time Congress enacted such a ban).  It mandated the return of escaped slaves (“Persons held to Service or Labour”).

Election Results:
On November 6, 1860, Republican Abraham Lincoln was elected president with an Electoral College majority greater than the combined total of his three opponents:  180 for Lincoln to 72 for Southern Democrat John Breckinridge, 39 for Constitutional Unionist John Bell, and 12 for Northern Democrat Stephen Douglas.  Lincoln won a plurality of the popular vote, 40% to Douglas’s 30%, Breckinridge’s 18%, and Bell’s 12%.

Secession:
On November 10, 1860, the South Carolina legislature became the first to call for a convention to consider seceding from the Union.  Delegates were elected on December 6, and the convention opened on December 17.  On December 20, 1860, delegates unanimously approved a secession resolution, making South Carolina the first of 11 Southern slave states to leave the Union. 

Crittenden Compromise:
On December 18, 1860, Senator John Crittenden of Kentucky, proposed six constitutional amendments and four congressional resolutions aimed at appeasing and keeping the slave states in the Union.  The proposed constitutional amendments would have:  (1) extended the old Missouri Compromise line to California, allowing slavery below and banning it above the line, and protecting slavery from congressional interference; (2) forbidden Congress from banning slavery on federal property in slave states (e.g., military posts); (3) prevented Congress from abolishing slavery in the District of Columbia as long as it was legal in Maryland and Virginia; (4) prohibited Congress from interfering with the interstate slave trade; (5) mandated Congress to compensate directly the owners of runaway slaves; and, (6) made the other five amendments and the 3/5 and fugitive slave clauses of the Constitution unrepealable.  His congressional resolutions offered stronger protection of the Fugitive Slave Law.  The Crittenden Compromise was not acceptable to President-elect Lincoln and most Republicans because it would have expanded slavery into the Western territories and given perpetual protection to the institution.