<p>In recent years, crop diversification has been promoted among management strategies demonstrating beneficial impacts on agricultural productivity and ecosystem health, thus providing a pathway toward sustainable agricultural futures. However, while some research has explored the conditions that enable or support systems that are both diverse and productive, there remains a need for further study to deepen our understanding across different regions and contexts. We address this gap by examining influencing factors and contexts that result in systems with high crop productivity and contrasting crop diversity trajectories. We conducted in-depth interviews with fifty agricultural stakeholders across four U.S. counties in two different regions, each pair of counties representing opposing trends in cropping system diversity since 2008. Our analysis identified five groups of factors that consistently influenced crop selection decisions and agricultural system change, encompassing economic, social, policy, techno-managerial, and biophysical factors. Our findings demonstrate more similarities than dissimilarities in the factors influencing farmer crop selection decisions across all counties. Subtle differences derived from how certain crop selection factors – such as climate variability, soil type, labor dynamics, and policies – interacted within specific contexts. Our findings suggest that biophysical variability and historical legacies of diverse cropping contribute to current patterns of diversification, with larger populations and alternative market demands further supporting diverse agricultural systems. This work reinforces the need to account for the dynamic contexts at local and regional levels in research and intervention aimed at promoting crop diversification.</p>