Santa Susana is a former railroad town located mostly within the City of Simi Valley and partly in the neighboring Los Angeles neighborhood of Chatsworth. A small portion of the community, outside the Simi Valley city limits to the south of the Ventura County Metrolink rail line, is an unincorporated area and census-designated place (CDP). The community is in the eastern part of the Simi Valley and on the western part of Chatsworth, Los Angeles, surrounding the Santa Susana Mountains. With 87.2% identifying as being Caucasian in the 2010 U.S. Census, the Santa Susana CDP has the fifth highest percentage of white residents in Los Angeles County.