St. Lawrence River, is a grand river and estuary, which along with the Great Lakes makes up a hydrographic system that goes 3,058 km into North America.
This river flows through the mean latitudes of the continent. It originates in Lake Ontario together with Kingston and then crosses the cities of Brockville and Cornwall (in Ontario Province), Montreal, Trois-Rivières and Quebec.
The psychological process called association
Its a multilateral system of trading in which a country pays for its imports from one country by its exports to another. Hope this answers your question :)