27 of the 55 delegates to the 1787 US Constitutional Convention were slaveowners [View all]

Just about half. These are their names:

Richard Bassett (DE)
Jacob Broom (DE)
John Dickinson (DE)
George Read (DE)
William Houstoun (GA)
William Few (GA)
William Samuel Johnson (CT)
Daniel Carroll (MD)
Luther Martin (MD)
John Francis Mercer (MD)
Daniel of St. Thomas Jenifer (MD)
William Livingston (NJ)
William Blount (NC)
William Richardson Davie (NC)
Alexander Martin (NC)
Richard Dobbs Spaight (NC)
Pierce Butler (SC)
Charles Cotesworth Pinckney (SC)
Charles Pinckney (SC)
John Rutledge (SC)
John Blair (VA)
James Madison (VA)
George Mason (VA)
Edmund Randolph (VA)
George Washington (VA)
George Wythe (VA)
Robert Morris (PA) (though he didn't actually own any slaves, he owned a slave ship and was heavily invested in the slave trade, so for all intents and purposes...

In addition, 12 of the 43 men who have served as President of the United States owned slaves, eight of whom owned slaves while serving as POTUS:

George Washington
Thomas Jefferson
James Madison
James Monroe
Andrew Jackson
Martin Van Buren
William Henry Harrison
John Tyler
James K. Polk
Zachary Taylor
Andrew Johnson
Ulysses S. Grant (mostly through his wife)

Additionally, James Buchanan was somewhat of a borderline case since his brother-in-law owned two slaves whom Buchanan bought and then hired as indentured servants.

Of those 12, only two (Washington and Jefferson) were delegates to the 1787 Constitutional Convention. So that's 10 other Presidents who owned slaves.

Just remember: the current President of the United States could very well have been owned by any one of the men listed above, had he lived within one and half to two or so centuries ago. And his successor as the Democratic presidential nominee, and likely (fingers crossed) successor as President of the United States, would also have been considered the property of her husband on the account of the fact that she is a she.

I don't think a lot of people - even a lot of Democrats/liberals/progressives/left-wingers - realize the significance of all of this. Really puts things into perspective, doesn't it?

Sobering.