Highway–Culture Spatial Match as the Decisive Factor for Transport–Culture–Tourism Coupling in Pastoral Borderlands

The integrated development of transportation, culture, and tourism is widely recognized as critical for regional sustainability, yet existing research predominantly uses two-dimensional frameworks and overlooks the unique constraints of highway-dominated pastoral borderlands. Taking Inner Mongolia (2023–2025) as a case study, this research develops a 24-indicator evaluation system and a multi-model analytical framework integrating entropy-weighted TOPSIS, coupling coordination, obstacle degree, and grey relational analysis. This study makes three contributions: (1) It constructs a highway-oriented three-dimensional evaluation framework suited for border regions spanning millions of square kilometres; (2) it distinguishes short-term static obstacles from long-term dynamic factors using an integrated multi-model chain; and (3) it proposes the theoretical concept of ‘Highway–Culture Spatial Matching’ for sparsely populated borderlands. The results reveal a significant spatial gradient, with high coordination in the Hohhot–Baotou–Ordos core and severe lagging in western pastoral areas. The spatial match between highway network accessibility and nomadic cultural heritage sites, rather than resource abundance alone, is the decisive factor determining system coupling. The obstacle degree model pinpoints highway mileage and road network density as primary short-term bottlenecks, while grey relational analysis confirms that the scale of the cultural tourism industry and intangible heritage activation are key long-term drivers. This work provides a quantifiable, evidence-based reference for formulating tiered, sustainable development policies in similar northern frontier ethnic regions, consistent with the UN 2030 Agenda for Sustainable Development.