In the 1930s, Chinese industries showed clusters near ports and spread to inland regions over time. The research looked at why this happened using data from that period. It found that both trade advantages and being near other industries played a big role in where industries developed. When trade thrived in an area, it helped businesses grow and attracted more companies to set up there. However, too many industries in one place made it crowded, pushing some to move to new areas. This finding can help China make better decisions about moving industries around and making sure development is fair.