Which factor best explains the high population density of the Great Lakes-St. Lawrence Lowlands?

• A. Desert conditions and poor water access.
• B. Cold Arctic climate.
• C. Rugged mountains hindering settlement.
• D. Favorable climate, fertile soils, and good access to water and transportation networks.

Answer: (D)

The key idea is how geography supports dense settlement. The Great Lakes–St. Lawrence Lowlands have a combination of a milder climate for Canada, fertile soils, and excellent access to water and transportation networks. The Great Lakes and the St. Lawrence River create a major transportation corridor that fuels trade, industry, and urban growth, so people concentrate where goods move easily. Fertile soils deposited by glaciers support productive farming, which sustains large populations, and the relatively longer growing season compared with the north makes farming viable near cities. All of this happens in a compact area with many cities and economic opportunities, leading to high population density. The other descriptions—desert conditions and poor water access, a cold Arctic climate, or rugged mountains hindering settlement—don’t fit this region, which is known for its waterways, accessible terrain, and favorable conditions for people to live and work.