In this work, we provide an additional constraint on emissions and trends of nitrogen oxides using nitrate wet deposition (NWD) fluxes over the United States and Europe from 1980–2020. We find that NWD measurements constrain total NO_x emissions well. We also find evidence of NO_x emission overestimates in both domains, but especially over Europe, where NO_x emissions are overestimated by a factor of 2. Reducing NO_x emissions over Europe improves model representation of ozone at the surface.