If you are an ArcGIS user, we recently published new data on ArcGIS Online. Search for it at arcgis.com with our handle, "usc_public."

The featured layer package shows 2010 census tracts within Alameda County displayed by majority ethnic group within each tract. In many census tracts, there is no racial group that comprises the true majority (over 50%) of the population in that tract. Therefore, we symbolized based on which group has plurality – which group represents the largest number. Look at the script for the field labeled "Most" to see how we did it.