Abstract: Fully unleashing the potential of public data as a production factor is crucial for building a unified national market and facilitating the smooth circulation of the domestic economy. To catalyze the latent value of public data,governments at various levels have spearheaded the establishment of public data access platforms,markedly improving the accessibility,reliability,and verifiability of government-held information. This study contends that public data access provides a unified,authoritative,and verifiable information infrastructure that materially informs supplier selection. First,the deployment of public data platforms in a destination city mitigates information asymmetry in cross-regional transactions. By lowering search costs and broadening the horizon for supplier discovery,it empowers firms to identify and onboard high-quality partners. Second,heightened transparency reduces the necessity for resource-intensive offline due diligence and continuous monitoring,thereby strengthening contractual enforceability and lowering ex-post contracting costs. Furthermore,the impact of public data access extends beyond mere structural reconfiguration. By optimizing supplier matching and improving operating efficiency,these platforms enhance a firm's broader competitive advantage. This study exploits the staggered establishment of city-level public data access platforms as a quasi-natural experiment,employing a staggered difference-in-differences (DID) design. Our results show that the launch of these platforms in destination cities leads to a statistically and economically significant increase in the share of procurement sourced from suppliers located in that city by listed firms. Mechanism analyses indicate that this effect operates through two primary channels:the mitigation of ex-ante information constraints in supplier selection and the reduction of ex-post monitoring and contracting frictions. With respect to the ex-ante selection mechanism,we construct three proxies for external information constraints,including the overall information environment of the supplier's city,whether the focal firm has prior procurement experience in the destination city,and whether the firm has established subsidiaries in that city. The results suggest that the positive effect of public data access on local procurement share is significantly stronger when external information constraints are higher. Regarding the ex-post supervision mechanism,we construct three variables capturing potential contracting costs,including the firm's dependence on key intermediate inputs,the credit risk borne by the firm in procurement transactions,and the trust environment of the supplier's region. The evidence shows that the procurement-enhancing effect of public data access is more pronounced among firms with greater potential contracting costs. Further tests on economic consequences show that as firms increase procurement from suppliers located in cities with public data access,their competitive advantage is significantly enhanced. We further examine the mechanisms through which a higher procurement share from data-access cities strengthens firms' competitiveness. First,public data access in supplier cities improves firms' ability to identify and select high-quality suppliers,thereby enhancing market competitiveness. Second,public data access enhances firms' competitive advantage by improving internal operational efficiency. This is reflected in a reduction in supply—demand mismatch risk at the supply chain level and an increase in total factor productivity at the production level. Together,improved supplier matching and higher operational efficiency explain how procurement reallocation toward data-transparent cities translates into stronger firm competitiveness. Our findings remain robust across dynamic parallel trend tests,placebo simulations,and extensive heterogeneity analyses. This study offers three primary contributions to the literature. First,we extend research on cross-regional supply chain configuration through the lens of digital governance. While prior studies emphasize physical infrastructure,market thickness,or firm traits as determinants of procurement geography,we show how government-led improvements in information infrastructure reshape the economics of search and contracting,thereby influencing supply chain design. Second,we enrich the discourse on the economic consequences of public data access. Whereas existing research focuses on financial reporting or innovation outcomes,we shift attention to supplier geography. By articulating the dual mechanisms of ex-ante selection and ex-post supervision,we demonstrate how data governance reforms alter supply chain quality and reshape market competition. Third,from a factor allocation perspective,we advance understanding of the synergy between data and traditional production inputs. Rather than viewing data solely as a driver of innovation,we provide micro-level evidence that data-driven institutional reforms reconfigure supply chains and optimize spatial resource allocation,thereby supporting coordinated domestic circulation and sustainable growth.