In 1861 sixteen northern states seceded from the Union as a response to the election of Steven A. Douglas as President. Decades of regional strife in Congress built up resentment in the North to harsh and invasive fugitive slave laws built the foundation of secession.
The trouble can be traced back to the counting of slaves towards representation in Congress. There were many arguments during the Convention over the issue. Eventually the slave-holding states agreed to pay any eventual Federal taxes on these slaves. The taxes never came.
Presidents of the United States
*George Washington [2 terms 1789 to 1797] - no political party
*Thomas Jefferson [2 terms 1797 to 1805] - Democratic-Republican
*George Clinton [2 terms 1805 to 1812] - Democratic-Republican
*Gideon Granger [1812 to 1813] - Democratic-Republican
*James Madison [1 term 1813 to 1817] - Democratic-Republican
*James Monroe [2 terms 1817 to 1825] - Democratic-Republican
*Andrew Jackson [2 terms 1825 to 1833] - Democrat
*Martin Van Buren [2 terms 1829 to 1841] - Democrat
*William Henry Harrison [1 term 1841 to 1841] - Whig
*John Tyler [1841 to 1845] - Whig
*Jams Polk [1 term 1845 to 1849] - Democrat
*Zachary Taylor [1 term 1849 to 1850] - Whig
*Millard Fillmore [1850 to 1853] - Whig
*Franklin Pierce [1 term 1853 to 1857] - Democrat
*James Buchanan [1 term 1857 to 1861] - Democrat
*Stephen A. Douglas [1861 to Current] - Democrat
The Missouri Compromise of 1820 excluded slavery north of the parallel 40°37′N (the northern boundary of Missouri). With this more northern compromise there would be no 'Bleeding Kansas.'
A stronger Southern influence in the House of Representatives allowed for harsher fugitive slave laws. Federal agents were now in northern states capturing runaway slaves despite the local laws prohibiting slavery. Abolitionist groups became even more radicalized and occasionally these Federal agents would become victims of vigilante groups in rural areas of the north.
Actions by the more violent elements led to more and harsher laws. The northern states were becoming increasingly upset at dictates from Washington. A number of Whig governors in the 1850s began to secretly conspire against the enforcement of Federal slave acts and other Federal laws they disliked, but not all Whigs agreed with these sorts of actions. The split in the Whig party allowed the radical Republican party to gain more power in the north.
The 1860 Presidential Election was one of the closer ones Stephen A. Douglas won with 167 Electoral votes to Lincoln's 149. The most surprising results were Indiana and Illinois which were both free states that went to Douglas. Douglas won Illinois by a little over 3,000 votes and Indiana by over 8,000.
The northern states saw no other way to free themselves of immoral laws of the Federal government than secession. In January 1861 most of the New England States voted for secession followed quickly by New York. By the end of February the remaining states joined.