Over the past several decades, the New York State Department of Environmental Conservation (NYSDEC) has monitored air quality in urban, suburban, and rural locations across the state. Such data are used to determine compliance with national ambient air quality standards (NAAQS), as well as track the effectiveness of pollutant emission controls. This paper summarizes the changes in gas-phase criteria and related pollutants on an annual, seasonal and diurnal basis across New York, USA. Annual average and peak concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) have decreased by 50% or more since 1980 across New York, generally consistent with anthropogenic emissions reductions across different source sectors over the past 35 years. At the same time, annual average concentrations of the secondary pollutant ozone (O3) appear flat or are increasing even though peak daily 8-hour concentrations have declined. This pollutant will likely remain a challenging public health issue for the foreseeable future.