This study employs longitudinal process tracing to examine overtourism in Barcelona (1986–2025), tracing its trajectory from an industrial port to global tourism hub. Drawing on 45 evidentiary units, Bayesian updating, and Collier’s (2011) diagnostic tests, we validate seven causal mechanisms: infrastructure lock-in, regulatory gaps, digital amplification, cultural commodification, resident resistance, governance fragmentation, and biopolitical erosion. These mechanisms interact through path-dependent feedback loops under neoliberal urbanization, generating housing crises, cultural erosion, and social conflict. Challenging linear destination life-cycle narratives, we propose the Cascade Amplification Framework, a five-layered model designed to mitigate overtourism and offer transferable insights for other urban tourism destinations facing similar pressures.
Shang et al. (2026) studied this question.