As high-speed rail (HSR) investment accelerates across China, the question of whether such large-scale infrastructure can promote balanced regional development or exacerbate spatial inequality has become central for policymakers and scholars. This study provides systematic micro-level evidence by analyzing a balanced panel of 353 county-level divisions, including urban districts, county-level cities, and counties, along the Shanghai-Kunming and Xuzhou-Lanzhou HSR corridors from 2008 to 2019. Usi...