States rights through slavery was the major cause of the Civil War, it was the issues of states rights that played the most important role. It was believed that all these 13 colonies would get equal representation in Congress and all these states were also seeking autonomy so they could at least make decisions regarding their internal matters. Both these things became impossible. While the states were granted some rights, it was declared in the Constitution that central government would be allowed to interfere in any important matters and its authority wouldn 't be questioned. Such articles in the constitution naturally gave alot powers to the central government, which created a rift between the states and the government. The minimum powers granted to states proved quite ineffective in appeasing them when the governments promise of equal representation to all states in the Congress was suddenly threatened by a population explosion in the North.
Purposes of the tariff
References: 1) The South Carolina Exposition 1828 http://www2.whidbey.com/chuckd/calhoun.html 2) Lincoln 's First Inaugural Address 1861 http://www.historyplace.com/lincoln/inaug-1.htm 3) The Presidents message to Congress in special session 1861 http://speaker.house.gov/library/texts/lincoln/spmsg.asp 4) John B. Gordon, Maj. Gen. CSA, "Reminiscences Of The Civil War", 1876 5) Gordon Leidner, Causes of the Civil War: A Balanced Answer, http://members.tripod.com/~greatamericanhistory/gr02013.htm