Sprawling low density cities consume resources too. Mass transit is less effective, so more people must buy and drive cars. Roads and highways are wider and more extensive. Cars need storage at the origin and destination of every trip, so homes need driveways or garages and businesses need parking lots. Other infrastructure must expand too: power lines, water/sewer pipes, communication wires, and so on.

One million people would need about the same amount of food/energy if they lived in 1,000 sq. mi. as they would if they lived in 100 sq. mi. But the cost per person to house and transport people in a dense city is lower than in a sprawling one.