imo, the key value and importance of NYC would be her state as the largest commercial centre for the whole USA, of which the states produce collectively the largest GDP on earth.
Just like many other commercial centres for individual countries in our human history. The merchants living in the commercial centre easily control the property/land rights as well as trading contracts of farming produces. Farmers can be guaranteed for the price and value of their upcoming output, sometimes with a down payment and contract from the merchants, promising to buy their produce. Therefore, the farmers can reduce their financial risk, especially when encountering unexpected bad weather just before collection/shipment.
The merchants often also gather intelligence/information, nationally and internationally, about the products produced by farmers. Such as (inter)national supply (including inventory and shipments) and demand. In order that not all farmers would plant the same products for a same year, according to merchants' contracts.
From a positive view, I think there is a kind of cooperation and join venture partnership between them. Can't just measure/ evaluate the contributions merely on physical activities. imo