Why was so much of the middle colony economy based on farming?

Most of the middle colony economies were based on farming, because:

1) The weather conditions (being neither too hot, nor too cold), made it suitable to start farms (usually of wheat and the like).

2) Soil conditions of the Middle Colonies, while they are not as good as those found in the south, allows for ordinary food to be grown, & were good in nutrients.

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congress also has implied powers, which derive from the necessary and proper clause of the constitution and permit congress "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states.