Digital Infrastructure and Urban Green Productivity: Reassessing the Broadband China Pilot Programme

Broadband expansion may support economic growth, but its green-productivity benefits remain uncertain. Establishing whether local designation delivers these benefits matters for evaluating digital investment. This paper assesses the Broadband China designation in 285 cities over 2008-2022, using cumulative green TFP and annual productivity change. A staggered difference-in-differences approach compares designation cohorts with never-designated cities. The average cumulative-productivity estimate is 0.0051 log points, or about 0.51%, with a 95% confidence interval of −0.96% to 2.00%. The annual-change estimate is also statistically indistinguishable from zero. With baseline adjustment, the cumulative estimate increases to 0.70% but remains statistically insignificant, and the joint pretreatment test no longer rejects. Non-rejection does not establish identification. Unadjusted pretreatment differences are concentrated primarily in the 2014 cohort. Removing that cohort, matching cities and excluding areas with partial treatment leave the average cumulative effect statistically insignificant. Resource-group contrasts remain exploratory because both groups exhibit pretreatment differences. The results do not establish automatic green-productivity gains from designation and emphasize the importance of outcome construction, sample selection and treatment geography.