ABSTRACT
Many cities have adopted net-zero emission pledges, yet little is known about why these commitments emerge or how their determinants shift under changing policy environments. Using a panel of 148 large US cities from 2016 to 2022, this study applies the Political Market Framework and employs discrete-time event-history models to examine how policy demand, policy supply and institutional conditions shape adoption decisions. Results show that civic capacity, political ideology, and horizontal diffusion drive adoption in the full period, but their influence varies sharply across institutional contexts. During federal disengagement (2016–2018), cities with less population, strong vulnerability signals, supportive state policies, or fiscal cushioning through federal aid are more likely to adopt. When federal engagement returned (2019–2022), education, population size, and neighbor adoption emerged as significant correlates of net-zero adoption. These findings extend the Political Market Framework by showing how federal contexts condition the adoption of ambitious climate commitments.