Final answer:
The Middle Colonies were known as the 'Breadbasket Colonies' due to their substantial grain production, particularly of wheat, which contributed to a diverse and robust economy.
Step-by-step explanation:
The Middle Colonies, which included New York, New Jersey, and Pennsylvania, were noted for their fertile soil suitable for growing a variety of crops, including wheat, corn, and rye. This agricultural productivity earned them the nickname 'Breadbasket Colonies.' Unlike the New England colonies, which were geared more towards self-sufficiency, and the Southern colonies, which were heavily dependent on tobacco, the Middle Colonies had a diverse economy that included not just farming, but also iron manufacturing and a growing merchant class. Their longer growing season, diverse population, and religious tolerance, especially in colonies like Pennsylvania, made them an economically sound and culturally varied region.