Final answer:
During the Industrial Revolution, the northern economy was supported by trade and commerce, cottage industries, and mining and manufacturing.
Step-by-step explanation:
During the Industrial Revolution, the northern economy began to support itself through a combination of trade and commerce, cottage industries, and mining and manufacturing. The expansion of trade and commerce allowed for the exchange of goods and services, both domestically and internationally. Cottage industries involved small-scale production of goods within people's homes, while mining and manufacturing industries produced raw materials and manufactured goods on a larger scale.