Urbanization change in a mega-event preparation context: A multidimensional assessment of Zhangjiakou, a medium-sized co-host city of the Beijing 2022 Winter Olympics

Urbanization is a key pathway for regional transformation and an important lens for assessing the legacy of mega sporting events. Focusing on Zhangjiakou City, co-host city of the Beijing 2022 Winter Olympics, this study constructs a multidimensional urbanization index covering population, economy, built-environment, and ecology using the CRITIC weighting method, and applies spatial autocorrelation analysis and GeoDetector to examine urbanization dynamics from 2017 to 2022. The main findings are as follows: (1) Zhangjiakou's total urbanization level increased by 20.68%; population, economic, and spatial urbanization improved, whereas ecological urbanization followed an inverted-U trajectory and declined by the end of the study period. (2) High-level urbanization areas expanded from the central urban core toward the northern region, and the share of districts/counties at medium level or above increased markedly. (3) Economic urbanization showed significant positive spatial autocorrelation, with high-high clusters concentrated in the central urban area and later extending to Zhuolu County. (4) The economic dimension consistently showed the strongest explanatory power, while urban economic density, per capita urban road area, population density distribution, and total urban population were the most stable explanatory factors. These findings show multidimensional and spatially uneven urbanization during the Olympic preparation period in a medium-sized co-host city.