Many non-native insect, disease, and weed pests of food, fiber, and nursery crops pose threats to the U.S. environment, agricultural production, and exports. In this study we focus on regulations controlling the spread of noxious weeds, especially the regulatory differences among US states and investigate the determinants of such regulations. With a simple game-theoretic framework, we derive cross-state regulatory congruence as a function of ecological and agronomic characteristics and stakeholder lobbying through political contributions. Empirical results suggest ecological and agronomic dissimilarities drive large cross-state differences in noxious weed regulation across states. However, evidence of stakeholder interests in shaping these regulations is found to be statistically significant. In particular, the seed industry appears to favor more uniform regulations among US states.