Which information would be most useful to a geographer identifying cultural region borders?

The most useful information for a geographer identifying cultural region borders is found in the sights travelers see along highways. This reflects the cultural landscapes and significant landmarks that often characterize different cultural regions. These sights might include historical sites, religious monuments, unique architectural styles, and local cultural festivals that contribute to a region's identity and sense of place. Observing what travelers encounter on their journeys provides insights into the shared values, traditions, and customs of the people in that area, which are key elements in defining cultural boundaries.

In contrast, population density in urban areas provides demographic information but does not inherently reveal cultural characteristics. Political boundaries established by states are often arbitrary and do not necessarily align with cultural regions, as they are drawn for governance rather than cultural significance. Climate variations can influence some aspects of culture, like agriculture or clothing styles; however, they do not directly delineate cultural borders as effectively as the tangible cultural indicators travelers experience.