[Moonman62]

From a labor productivity standpoint, they were not as valuable as free labor... but. Unlike free labor, they had very high market value -- could be bought, sold or used as collateral and they reproduced at a high rate. You couldn't sell the children of free labor, but you could sell slave children.

Owners also got three fifths of a vote for every slave. It was a despicable system.

[Ditto]

Owners also got three fifths of a vote for every slave.

They didn't get any extra votes at the polls, but they did get extra Representatives in Congress and by extension, extra votes in the Electoral College.

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 relative to voters. 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.