This study examines spatially dynamic diffusion processes of local policy adoption among municipal governments. Using city-level climate action plans (CAPs) adopted in the Southern California region during 2000-2018 as a study frame, our analysis unpacks spatial variations in the effects of geographic neighbors and regional leaders on local policy diffusion processes. We first argue that both factors will spur CAP diffusion among city governments. We then develop a novel hypothesis of a spatial moderating effect between these two influences. Specifically, we theorize that adjacent neighboring diffusion effects will be less prominent in the areas with nearby regional innovators, while neighboring effects will be more prominent in the absence of regional policy leadership. To examine this, we first use traditional event history and logistic regression analyses. We then investigate inter-city diffusion dynamics in greater detail with a novel geographically weighted regression (GWR) method that unravels regional variations in local diffusion effects. Our aggregate analysis finds that both geographic neighbors and regional leaders drive the diffusion of local CAP adoptions. The novel application of GWR further shows marked spatial variations within the region, suggesting that neighboring proximity-driven diffusion effects are muted by the influence of regional leaders. By spatially unpacking the effect of geographic proximity and regional leadership in policy diffusion, this study enhances our understanding of dynamic and varied diffusion processes.

本研究考察了市政府间地方政策采用的空间动态扩散过程。我们以 2000 年至 2018 年南加州地区采用的城市级气候行动计划 (CAP) 作为研究框架，分析了地理邻居和地区领导者对当地政策扩散过程影响的空间变化。我们首先认为这两个因素都会刺激 CAP 在城市政府之间的传播。然后，我们提出了关于这两种影响之间的空间调节效应的新假设。具体来说，我们的理论是，在区域创新者附近的地区，相邻扩散效应不太明显，而在缺乏区域政策领导的情况下，相邻效应将更加突出。为了检验这一点，我们首先使用传统的事件历史和逻辑回归分析。然后，我们使用一种新颖的地理加权回归（GWR）方法更详细地研究城市间扩散动态，该方法揭示了局部扩散效应的区域差异。我们的综合分析发现，地理邻国和地区领导者推动了当地 CAP 采用的传播。 GWR 的新颖应用进一步显示了该地区内显着的空间变化，表明邻近邻近驱动的扩散效应因地区领导人的影响而减弱。通过在空间上揭示地理邻近性和区域领导力对政策扩散的影响，这项研究增强了我们对动态和多样化扩散过程的理解。