...as anyone who has spent, say, five minutes studying the U.S. Constitution and its history is fully aware the famous "three-fifths clause" was a compromise by the anti-slavery forces to keep slave-owners from being over-represented in the U.S. House of Representatives where population determined -- then as now -- the number of congressional seats per state. If slaves, specifically mentioned as "persons" in Article 1, Section 2, Paragraph 3 ("three fifths of all other Persons") were counted, the Southern slave-owners would have an even greater numerical advantage in Congress than they already were destined to have. With slaves counted as a whole person, slave owners' power would increase -- while slaves would be unable to ever win their freedom in a system dominated by slaveowners. Hence the compromise, which was in fact pushed by anti-slavery forces.
The population in the North would grow -- eventually destined to overwhelm the South in numbers. This was one of the reasons for the Dred Scott decision -- a desperate attempt to write slavery into the Constitution forever, written by the slave-holding Roger Taney -- the Democrat who was Chief Justice of the United States.--Jeff Lord, AmSpec