Measurement and spatiotemporal evolution of spatial agglomeration in China’s hog industry an EG-index analysis based on prefecture-level data

Accurately characterizing the spatial deviation of hog slaughter across prefecture-level cities within a province relative to the agricultural production base is essential for understanding adjustments in hog-production capacity and for advancing differentiated regional governance. Using prefecture-level hog slaughter, the gross output value of agriculture, forestry, animal husbandry and fishery, and provincial farm-size structure data for 30 mainland Chinese provinces from 2007 to 2023, this study constructs an intra-provincial Ellison-Glaeser (EG) index. Markov transitions, spatial Markov analysis, club convergence and the optimal-parameters-based geographical detector (OPGD) are then used to examine the dynamic evolution of intra-provincial spatial organization and its influencing factors. The results show that: (1) the national mean EG index increased with fluctuations, whereas the median remained broadly stable, indicating that the rise in relative spatial deviation was driven mainly by a small number of high-EG provinces; (2) Qinghai, Xinjiang, Shanghai and Inner Mongolia recorded relatively high EG values, whereas the traditional hog-producing provinces of Sichuan, Hunan, Henan and Hebei recorded relatively low values. The net-exporting areas also had lower EG levels than the major consuming and balanced production-consumption areas, suggesting a closer spatial match between hog slaughter and the agricultural production base in traditional producing regions; (3) EG states displayed strong path dependence and spatial association, with conditional transition probabilities varying across neighboring EG environments, while provinces formed three relatively stable high-, medium- and low-EG evolutionary tiers rather than converging as a whole; and (4) the leading factor varied by period: agricultural industrial structure was most prominent in 2007–2012, mean annual temperature in 2013–2018, and the corn-production base in 2019–2023, although the evidence for the last period was weak. The study extends hog-industry agglomeration research from an intra-provincial relative-spatial-organization perspective and provides evidence for improving production layout and differentiated regional governance.