The U.S. Geological Survey (USGS) is developing SPARROW models (SPAtially Related Regressions On Watershed Attributes) to assess the transport of contaminants (for example, sediment and nutrients) through the Pacific drainages of the United States (the Columbia River basin; the coastal drainages of Washington, Oregon, and California; the Klamath River basin; the Central Valley of California, and the west slopes of the Sierra Nevada Mountains). SPARROW relates instream water quality measurements to spatially referenced characteristics of watersheds, including contaminant sources and the factors influencing terrestrial and aquatic transport. Cattle grazing intensity is a potential factor affecting sediment and nutrient delivery to streams. The spatial data set “Distribution of grazing cattle within the Pacific drainages of the United States (2012))" represents an estimate of the distribution of grazing cattle on potential grazing land in 2012. This data set was created by disaggregating 2012 county-level values for the number of cattle not housed in an animal feeding operations (such as a dairy or feedlots) to the potential grazing land within each county. The resulting raster data set represents the number of grazing cattle per each grid cell of potential grazing land.