From PLOS, Urbanization is correlated with economic growth, but it is not necessarily the cause of it.

The authors of the study argue that GDP growth may create conditions that organically drive migration from rural to urban areas, but the assumption that urbanization will necessarily drive strong economic growth may be false. Pointing to the numerous examples of accelerated urbanization without strong economic growth (again, the green graph above), they caution that “urbanization is not an automatic panacea” for economic difficulties. Citing other work, the authors suggest that instead of trying to move people into cities, governments and development agencies should focus on creating a mobile workforce, ensuring broad access to goods and markets, implementing government policies that support commerce, and investing in infrastructure. These efforts could make a bigger difference for short- and medium-term economic growth than arbitrary urbanization targets.

While economic growth is an incredibly complex process and much work remains, this study serves as a good reminder not to confuse causation and correlation: just because two variables are closely related doesn’t necessarily mean that one directly causes the other.