One thing that many do not realize was that up to this point in time, the "Entire" Federal budget was derived from Tariffs. Approximately 80% of these tariffs were on Southern products, so the South was paying about that 80% of the Federal Budget, A new Tariff law had passed through Congress which would up the tariff from around 10-13% to as much as 40% on some items. The house had a large northern majority so it passed readily through the house. The Senate was evenly divided, but one traitor from my home state of TN voted for it, Andrew Johnson, who would later become Lincoln's VP.

The major difference between the Revolution was that the revolutionaries cried Taxation Without Representation, the South did have representation, just not enough to keep from being run over in a Roughshod manner, They finally had enough.

It is totally true that Slavery was an issue in the nation at the time. It was however not the "Sole" reason for the war, in Fact, not even the Major issue.
One further comment on what Flintfan said. The vast amount of territory which was acquired as a result of the Mexican war had been won primarily by Soldiers made up from the South, in Fact, this was when TN gained its Nickname as the "Volunteer" state. When it was proclaimed that all these territories would remain Slave Free until such time as they might attain statehood, the South was not so STUPID (Not directed toward you Flintfan), as to not realize this would Skew the Balance of Power even further away from them & toward the North.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra