This study explores the persistence and transformation of culture amidst a critical economic process in China today, known as urbanization. Based on the China Labor-force Dynamics Survey (CLDS), we find that the clan, a central mechanism used to sustain cooperation in China's rural society, continues to impact trust traits amidst the ongoing urbanization process. Respondents from regions with a history of high clan density report higher levels of limited trust toward families, lower levels of generalized trust toward strangers, and a significant trust gap between these two. Nevertheless, the urbanization process is gradually mitigating the effect of clans on trust traits by driving the population from villages, providing public services to citizens, and promoting cooperation among strangers. •This study examines cultural persistence and changes during China's urbanization.•Clan system still influences trust traits during rapid urbanization process.•High clan density regions show larger trust gap between families and strangers.•Urbanization is mitigating clans' effect on trust traits.•It does so by moving populations, offering public services, and fostering stranger cooperation.