July 2, 1776- The Deceleration of Independence was signed, a document which declared the secession of the 13 American Colonies from England. This set up the idea of the right to secede in America.
November 15, 1777- The Articles of Confederation was adopted by the Continental Congress. This document established the idea of "states rights" and supported an anti-federalist attitude.
June 21, 1788- The United States Constitution was ratified and put into full effect. This put an end to the Articles of Confederation, and created a strong federal government.
March 3, 1820- The Missouri Compromise was created, which prohibited slavery in all territory gained by the Louisiana Purchase north of Arkansas, except for the state of Missouri.
November 24, 1832- The Nullification Crisis occurred, which was a struggle of power between the state of South Carolina and the federal government after South Carolina attempted to nullify a tariff that the federal government passed. This was the first real threat of secession.
March 30, 1854- The Kansas-Nebraska Act was passed, which allowed the states of Kansas and Nebraska to enter the United States as either a slave or a free state, decided by popular sovereignty, which repealed the Missouri Compromise. This created a division between the North and the South as they both attempted to gain the territory for their beliefs.
November 6, 1860- Abraham Lincoln was elected President of the United States of America. He was the first Republican president, and was believed to be a strong abolitionist and federalist, both of which the South was opposed to.
December 20, 1860- South Carolina officially secedes from the United States of America. They were shortly followed by Mississippi, Florida, Alabama, Georgia, Louisiana, Texas, Virginia, Arkansas, North Carolina, and Tennessee.
April 12, 1861- The Civil War began, bringing a climax to the turmoil that had been building up in America since we had won our independence.
April 9, 1865- The Civil War ended, officially rejoining the Union.
December 6, 1865- The 13th Amendment was ratified and put into effect. This officially put an end to slavery throughout the United States.