What are reasons why slavery was not as important in the north as in the south

Slavery was not as prevalent in the North as it was in the South due to economic and geographic factors.

The key factor was the type of economy in the North versus the South.

Very quickly, the Northern economy became based on industry while the Southern economy was largely based on large scale plantation style farms.

The end result was that the South needed slaves more for their type of economy to be profitable.