Final answer:
The largest densely populated area in Canada and the United States is the Northeast Megalopolis, which includes cities like New York City and Boston.
Step-by-step explanation:
The largest area in Canada and the United States that is densely populated (over 250 people per square mile) is the megalopolis that forms the corridor from Washington, D.C. to Boston. This area is known as the Northeast Megalopolis or the BosWash Megalopolis.
Four cities in this area include:
- New York City, New York
- Philadelphia, Pennsylvania
- Baltimore, Maryland
- Boston, Massachusetts