Spain boasts Europe's largest high-speed rail (HSR) network, connecting Madrid with its autonomous communities under the banner of socioeconomic convergence. However, the expansion of this network raises questions about its political motivations and impacts. Why has the Spanish government prioritized connecting Madrid to certain regions over others? How do these infrastructure choices influence regional autonomy and identity politics? This paper argues that Spain’s HSR strategy is driven by a dual political agenda: fostering economic cohesion while countering regional independence movements. The central government prioritizes HSR investments in regions with distinct languages and significant support for independence, such as Catalonia. By facilitating travel, the state aims to integrate these regions economically and culturally into the national framework. Yet, this strategy often backfires, exacerbating local concerns over cultural preservation and economic redistribution. Through a subnational analysis of HSR expansion from 1992 to 2023, this research combines survival analysis of construction timelines with fieldwork in key regions, including Catalonia, the Basque Country, and Andalusia. Interviews with local stakeholders reveal mixed perceptions of HSR’s economic benefits and its impact on cultural identity and policy autonomy. This work contributes to understanding how transportation infrastructure can reshape center-periphery dynamics, even in advanced democracies. The findings shed light on Spain’s contentious regional politics and provide broader insights into the intersection of infrastructure, identity, and political power.