citiesbetween

Citiesbetween is a term used in geographic information systems to describe the set of cities that lie along, or in proximity to, the route between two specified endpoints. The concept can be implemented as a function, query, or dataset that returns cities located on the path between two points, or within a defined tolerance of that path. Variants distinguish between cities that lie strictly on the great-circle route and those that fall within a corridor around it.

Implementation relies on geographic coordinates from city reference datasets such as GeoNames or OpenStreetMap. Typical methods involve calculating the geodesic (great-circle) path between the endpoints and testing whether other city coordinates lie within a specified distance from that path. An additional consideration is whether a city must be between the endpoints along the route, or simply near the line extending beyond the endpoints.

Applications of citiesbetween include travel planning, logistics optimization, regional analysis, and historical or demographic studies that examine settlements connected by a common corridor. It also supports visualization in maps and route-based analyses. Limitations include dependence on the quality and granularity of the underlying city database, the choice of distance tolerance, and the handling of irregular geographies such as islands or peninsulas. Computational cost can be a factor when processing large datasets or tight tolerances.

In practice, citiesbetween can be realized through geographic information system tools or custom code that combines geodesic calculations with spatial queries. It is related to concepts such as great-circle distance, route planning, and proximity analysis, and is commonly used to identify regional clusters of settlements along or near a transit or travel path.