What economic activity helped new york city and philadelphia to grow?

Both New York City and Philadelphia are located on major waterways, which made them ideal locations for shipping and trade. New York City is located at the mouth of the Hudson River, which provides access to the Atlantic Ocean. Philadelphia is located on the Delaware River, which provides access to the Delaware Bay and the Atlantic Ocean.

The presence of these waterways allowed both cities to become major centers of commerce and trade. Goods could be easily transported to and from the cities by ship, which made them ideal locations for businesses and warehouses. As a result, both cities grew rapidly in the 18th and 19th centuries.

In addition to shipping and trade, New York City and Philadelphia also benefited from other economic activities, such as manufacturing, finance, and tourism. However, shipping and trade were the foundation of their economic growth.