Answer:
A frigid climate and rocky soil prevented the region from developing a cash crop.
Explanation:
The main reason why hundreds of thousands of enslaved Africans were brought to the American colonies was the existence of large plantations where cash crops such as tobacco, rice, indigo, sugar, and cotton were grown.
These cash crops required warm climates, good soils, and more or less humid conditions which were not present in New England.
The Puritans, who made up the majority of the population in New England, also had stronger moral objectios against slavery (this is why abolitionism was so strong in New England), but from a materalist point of view, the answer is what was explained above.