<p>A historical dataset of river chemistry and discharge is presented for 140 monitoring sites along the United States East Coast, the Gulf of Mexico, and the West Coast from 1950 to 2020. The dataset, referred to here as River Chemistry for the U.S. Coast (RC4USCoast), is mostly derived from the Water Quality Database of the U.S. Geological Survey (USGS), but also includes river discharge from the USGS’s Surface-Water Monthly Statistics for the Nation and the U.S. Army Corps of Engineers. RC4USCoast provides monthly time series as well as long-term averaged monthly climatological patterns for twenty variables including alkalinity and dissolved inorganic carbon concentration. It is mainly intended as a data product for regional ocean biogeochemical models and carbon chemistry studies in the U.S. coastal regions. Here we present the method to derive RC4USCoast and briefly describe the river's carbonate chemistry patterns.</p>