This article studies atmospheric nitrogen (N) deposition in urban areas on two native prairie grass species, Schizachyrium scoparium and Nasella leucotricha. Findings indicate that while native prairie grasses may exhibit a positive biomass response to increased N deposition up to ~18 kg ha⁻¹ yr⁻¹, total inorganic N deposition is well above the estimated critical load for herbaceous plant species richness in the tallgrass prairie of the Great Plains ecoregion and thus may negatively affect these plant communities.