What does the Rank-Size Rule describe about city distributions in urban systems?

What does the Rank-Size Rule describe about city distributions in urban systems?

• A. The nth largest city is roughly 1/n the size of the largest; indicates primacy if one city dominates
• B. The sum of city sizes equals the square of the largest city
• C. Population sizes are equal across all cities
• D. City sizes are random with no pattern

Answer: (A)

The idea being tested is how city sizes tend to distribute in an urban system: as you rank cities from largest to smallest, each city's population tends to be roughly inversely related to its rank. This means the largest city sets a reference, the second-largest is about half as large, the third about a third, and so on. This pattern is the Rank-Size Rule, often described as Zipf’s law in geography. It helps explain primacy because when one city greatly dominates in size, the sequence shows a strong disparity between the top city and the rest. Saying that the nth largest city is roughly 1/n the size of the largest captures that inverse relationship and the potential for a dominant city. The other options don’t fit this pattern: equal sizes imply no rank-based distribution, summing to the square of the largest isn’t how city sizes scale, and randomness would show no consistent pattern.

The idea being tested is how city sizes tend to distribute in an urban system: as you rank cities from largest to smallest, each city's population tends to be roughly inversely related to its rank. This means the largest city sets a reference, the second-largest is about half as large, the third about a third, and so on. This pattern is the Rank-Size Rule, often described as Zipf’s law in geography. It helps explain primacy because when one city greatly dominates in size, the sequence shows a strong disparity between the top city and the rest. Saying that the nth largest city is roughly 1/n the size of the largest captures that inverse relationship and the potential for a dominant city. The other options don’t fit this pattern: equal sizes imply no rank-based distribution, summing to the square of the largest isn’t how city sizes scale, and randomness would show no consistent pattern.