Nationwide diffusion of China's Transit Metropolis Pilot Program

China's Transit Metropolis Pilot (TMP) program is the world's most extensive initiative of its kind. Launched by the national government in 2010, the program has expanded to 117 mainland cities. This study employs a six-pronged policy diffusion framework to investigate the rapid adoption of the TMP nationwide. We analyze data from 280 larger cities between 2010 and 2017 using discrete event history analysis. Our findings indicate that the TMP program has been adopted primarily by cities with large populations, where there is high demand for public transport services and sufficient road space to support the expansion of public transport. The diffusion of the TMP program has been facilitated by contributions from every level of government, including the Ministry of Transport and provincial and prefectural authorities. Horizontal forces, such as intra-provincial competition, have played a role, too. Despite its success, the TMP program's diffusion has faced several local-level constraints, such as inadequate public transport infrastructure, lack of comprehensive Public Transport Development Plans, and weak fiscal capacity. Additionally, cities with a lower administrative status have been less successful in applying for or being selected as TMP cities. Over time, local governments' motivations for adopting the TMP program have evolved, reflecting changing priorities and conditions.