In this paper, I examine the unintended effects of Weibo’s geographic tagging policy, an effort intended to “Build a National Wall” against foreign influence but instead resulted in creating “Provincial Walls” within China. Drawing on a unique high-frequency panel data from 200 influential Weibo accounts and a data leakage incident, I demonstrate that the policy yields effective control over information by reducing both the participation in discussions and the volume of information that could threaten the regime. This is not achieved by suppressing overseas users, as initially intended, but rather by deterring out-of-province domestic users from participating in provincial public affairs discussions. However, such policy bolsters geographic identity salience, elevates the participation of local users in local affairs discussions, and deepens regional disparities. Our study highlights the complex, multifaceted impacts of such information control policies. While they may confer short-term benefits to the regime in terms of information control, they may inadvertently amplify longer-term threats to the regime by escalating societal tensions, aggravating the dictator’s informational dilemma, and fostering conditions conducive to collective action in authoritarian regimes.