International friendship cities, spatial spillover effect and urban export growth: Evidence from China

Abstract Using a spatial econometric model, this study investigates the impact of international friendship cities on urban exports in China at the city level. The results demonstrate a significant spatial spillover effect of international friendship cities on China's urban exports, benefiting not only the local area but also the neighbouring cities. Mechanism tests indicate that international friendship cities foster export growth in both local and adjacent cities by accumulating international social capital. Additionally, we identify a spatial spillover interval (within 700 km) and a siphonic interval (beyond 800 km) in the effect of international friendship cities on the urban exports of surrounding cities. This study sheds light on the role of international friendship cities in driving urban export growth in China.