Matt Walsh is right here. 

And being from Massachusetts, we were the first land in the world to permanently abolish this—until then—universal of human existence with the 1783 Quock Walker and Mum Bett cases.

"All men are born free and equal" reads the Massachusetts Constitution of 1780, still in force.

And it was on that declaration that Chief Justice William Cushing instructed the jury in the 1783 Quock Walker case: 

"...whatever sentiments have formerly prevailed in this particular or slid in upon us by the example of others, a different idea has taken place with the people of America, more favorable to the natural rights of mankind, and to that natural, innate desire of Liberty, with which Heaven (without regard to color, complexion, or shape of noses—features) has inspired all the human race. And upon this ground our Constitution of Government, by which the people of this Commonwealth have solemnly bound themselves, sets out with declaring that all men are born free and equal—and that every subject is entitled to liberty, and to have it guarded by the laws, as well as life and property—and in short is totally repugnant to the idea of being born slaves. This being the case, I think the idea of slavery is inconsistent with our own conduct and Constitution; and there can be no such thing as perpetual servitude of a rational creature, unless his liberty is forfeited by some criminal conduct or given up by personal consent or contract."