Sustainable cultural tourism in second-tier destinations: the impact of a cultural event portfolio

Culture emerges within event portfolio research as a strategic tool to foster sustainable tourism development in second-tier cities, given their role as drivers of economic and regional diversification. Yet, empirical evidence on the effectiveness of cultural event portfolios in these contexts remains limited. This study analyses Italy's joint 2023 Capitals of Culture, Bergamo and Brescia, using daily-aggregated mobile phone data (2021–2024) to test whether cultural event portfolios enhance attractiveness and guarantee temporal sustainability. The difference-in-differences methodology employed demonstrates the positive effect on tourism volumes, while the Gini index decomposition confirms that the initiative stabilises flows across the year. This study extends event portfolio literature by integrating cultural aspects and sustainability metrics, offering policy insights for managing tourism dynamics. • Frames culture's role in event portfolio strategy and second-tier destinations development. • DiD results show an increase in tourist volumes in both the short and medium term. • Suggests a dual role of cultural event portfolios from tourism provenance patterns. • Sustainability is framed into the evaluation of event-based development strategies. • Cultural event portfolios foster balanced tourism growth in second-tier destinations.