Here's a bit of what Nathanael quotes.
Connecticut became an economic powerhouse in the 18th century, far out of proportion to its tiny size, because we grew and shipped food to help feed millions of slaves, in the West Indies.
The rivers and streams of Connecticut in the 19th century were crowded with more than a hundred textile mills that relied on cotton grown by hundreds of thousands of slaves, in the South.
Up to the edge of the 20th century, two towns on the Connecticut River were a national center for ivory production, milling hundreds of thousands of tons of elephant tusks procured through the enslavement or death of more than a million people, in Africa.
Harriet Beecher Stowe, Hartford's most famous abolitionist, said this was slavery the way Northerners like it:
All of the benefits and none of the screams.