Why was slavery in the northern colonies of america only on a small scale

Slavery did not become a force in the northern colonies mainly because of economic reasons. Cold weather and poor soil could not support such a farm economy as was found in the South. As a result, the North came to depend on manufacturing and trade. Trade was the way colonists got the English goods they needed.

Explanation:

they didnt have enough to last themself let alone slaves

Why the southern colonies had large amounts of slavery ...

The southern colonies had lots of slavery because of how many plantations were used. Purchasing slaves were much cheaper than paying workers.

The northern colonies did not have slavery because the north did not depend on slavery for their economy. The northern colonies were not focused on farming and therefore did not need slavery.