Surveys of the butterfly fauna at single sites in endangered coastal sage scrub (CSS) habitat in southern California are rare. Here we resurrect historical records of the butterfly species encountered at Hall Canyon, a relatively undisturbed CSS site in the coastal foothills adjacent to Ventura, Ventura County, California, obtained over an eight-year period of collecting and observation from 1955 to 1962. A total of 57 species was recorded from an area of <5 km², representing half of the total species presently recorded for Ventura County. Documentation of past species richness at this site provides important background data for assessing future range shifts and changes in butterfly diversity related to urbanization and its effect on the health of the remaining CSS habitat in southern California.