Riverbank is a city in Stanislaus County, California, United States. The population was 24,623 at the 2020 census, up from 15,826 at the 20…Riverbank is a city in Stanislaus County, California, United States. The population was 24,623 at the 2020 census, up from 15,826 at the 2000 census. Incorporated on August 23, 1922, Riverbank's official slogan is "City of Action." It is part of the Modesto Metropolitan Statistical Area.