A model that holds that the potential use of a service at a particular location is directly related to the number of people in a location and inversely related to the distance people must travel to reach the service.

• A. Non-basic industries
• B. Basic Industries
• C. Gravity Model
• D. Threshold

Answer: (C)

The key idea is a spatial interaction model that treats places like gravitational attractions: the potential use of a service at a location increases with the size of the local population and decreases as the distance to the service grows. This is the Gravity Model, which formalizes how demand is drawn from nearby populations and how travel distance (or travel time) dampens that demand. In practice, visits or exchanges between places rise with more people on the origin side and fall when the barrier of distance makes travel less appealing, often including a distance-decay factor.

Other concepts describe different ideas. Basic vs. non-basic industries categorize whether industries serve local needs or export to other areas, not about how distance and population together shape the likelihood of service use. Threshold concerns the minimum market size needed for a service to be viable but doesn’t incorporate how distance or population at other locations affects likelihood of use.