The Political Costs of the 3/5th Clause/Compromise

From Wikipedia:

The three-fifths ratio was not a new concept. It originated with a 1783 amendment proposed to the Articles of Confederation. The amendment was to have changed the basis for determining the wealth of each state, and hence its tax obligations, from real estate to population, as a measure of ability to produce wealth.

The proposed ratio was, however, a ready solution to the impasse that arose during the Constitutional Convention. In that situation, the alignment of the contending forces was the reverse of what had obtained under the Articles of Confederation. In amending the Articles, the North wanted slaves to count for more than the South did, because the objective was to determine taxes paid by the states to the federal government. In the Constitutional Convention, the more important issue was representation in Congress, so the South wanted slaves to count for more than the North did.

The three-fifths ratio, or "Federal ratio" had a major effect on pre-Civil War political affairs due to the disproportionate representation of slaveholding states. For example, in 1793 slave states would have been apportioned 33 seats in the House of Representatives had the seats been assigned based on the free population; instead they were apportioned 47. In 1812, slaveholding states had 76 instead of the 59 they would have had; in 1833, 98 instead of 73. As a result, southerners dominated the Presidency, the Speakership of the House, and the Supreme Court in the period prior to the Civil War.

Free and Slave Population of the Southern Confederacy
The first number is the year
then the white population
then the slave population

1790
1,240,454
654,121

1800
1,691,892
851,532

1810
2,118,144
1,103,700

1820
2,867,454
1,509,904

1830
3,614,600
1,983,860

1840
4,601,873
2,481,390

1850
6,184,477
3,200,364

1860
8,036,700
3,950,511