Studies have shown that the illicit trafficking and consumption of counterfeit and substandard drugs have become one of the fastest-growing criminal enterprises during the past two decades globally. To date, China's counterfeit drug crime situation is exceptionally serious and there is an urgent need for its prevention and control in society, but geographic research in China has not covered this topic. Using data on 18203 sales-based counterfeit drug crimes in 367 cities in China from 2014 to 2019, this study explored the spatio-temporal evolution and regional types of China's sales-based counterfeit drug crimes by Thiel index, Herfindahl index, exploratory spatial data analysis, k-medoids clustering algorithm, and word cloud analysis. The main findings can be summarized into four aspects. 1) China's sales-based counterfeit drug crimes have evolved in two phases: first, the rise in sales-based counterfeit drug crime from 2014 to 2015 and the increase in inter-city differences; second, its decline after 2016 and the weakening of inter-city differences. 2) China's sales-based counterfeit drug crimes gradually spread from the southeastern coastal areas to the northern and central regions and evolved from a single-core or dual-core clustered distribution form to a multi-core diffusion distribution form and constitutes a more obvious "herringbone" band distribution pattern. 3) The spatial autocorrelation of China's sales-based counterfeit drug crimes is significant, and the clustering is unstable, with the migration and diffusion of high-high and low-high clustering areas, and showing a simultaneous clustering in the northern and central regions consistent with the overall pattern of sales-based counterfeit drug crimes. 4) In China's urban system, the changes in sales-based counterfeit drug crimes can be divided into four regional types, including rising cities, falling cities, fluctuating cities, and low-level cities, and the number and distribution of cities in each type are significantly different. For example, rising cities are mainly concentrated in the northern region, including Baoding, Taiyuan, and Beijing; falling cities are mainly distributed in Guangdong Province, including Guangzhou, Shenzhen, Zhuhai, Foshan, Jiangmen, and Zhongshan; fluctuating cities are concentrated in Jiangsu and Zhejiang Provinces, the central China plains, the Northeast, and the western region; and low-level cities are the most numerous and widely distributed. These findings are informative for crime prevention and social governance. For example, in cities of rising crime, we can strengthen the supervision of the online purchase and logistics of beauty and health supplement drugs; in cities of falling crime, we can focus on investigating the sales of special effect or specialty drugs in physical stores; in cities of fluctuating crime, we can promote and establish a collaborative mechanism to jointly combat sales-based counterfeit drug crimes. This study contributes to filling the gap in crime geography in China on counterfeit drug crime research.
