What does the gravity model predict about interactions between cities or neighborhoods?

• A. Interaction declines with distance and increases with the size or attractiveness of locations.
• B. Interaction increases with distance and decreases with size.
• C. Distance has no effect on interaction.
• D. Interaction depends only on cultural similarity.

Answer: (B)

A gravity-model view of spatial interaction says that places with more size or attractiveness pull more interaction, but distance acts as a friction that reduces how much interaction occurs. In this framework, interaction between two places grows as their size (or mass) increases, and it diminishes as the distance between them increases. A common way to express this is that I_ij is proportional to the product of the two places’ sizes divided by distance to some power, showing the opposing effects of size and distance.

So the best statement is that interactions decline with distance and increase with the size or attractiveness of locations. The other ideas—interaction increasing with distance, distance having no effect, or interaction depending only on cultural similarity—do not fit this gravity-based perspective.