Many non-native weed pests of food, fiber, and nursery crops pose threats to the U.S. environment and agriculture. We focus on regulations controlling the spread of noxious weeds, and especially the determinants of regulatory differences across U.S. states. 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. However, evidence of stakeholder interests is statistically and economically significant. Unlike in the seed industry, commodity producers do not favor regulatory uniformity.