Keystone Cemetery in Keystone, South Dakota occupies a landscape position of particular significance to the region's industrial and monumental history, positioned in proximity to Mount Rushmore and its vast memorial sculpture project that dominated economic and demographic patterns throughout the Black Hills. The cemetery grounds contain the interred remains of individuals from divergent historical periods, from earliest settlers through contemporary burials, with particular historical significance attaching to graves of workers engaged in the Mount Rushmore carving project that transformed the Black Hills landscape beginning in 1927. The cemetery documents the human costs of this ambitious artistic undertaking through grave markers of workers and laborers who died while engaged in or connected to the project. The terrain of the cemetery reflects the topography of the Black Hills region, creating a landscape of memory mirroring the dramatic geography. Among the notable individuals interred at Keystone Cemetery is Wild Horse Harry Hardin, a colorful figure in regional oral tradition whose grave marker and associated stories have become a site of particular interest to visitors and researchers. Harry Hardin's biographical narrative reflects aspects of American frontier mythology and the adventurous individuals attracted to the Black Hills during resource exploitation and economic development. Multiple Mount Rushmore workers and laborers are commemorated through grave markers distributed across the cemetery grounds, representing the mortality and human expenditure involved in executing this monumental artistic project. Catherine Haynes and Bobby Buntrock, individuals whose biographical details connect to the broader regional history of the Black Hills, are also interred at Keystone Cemetery. The cemetery's function as a repository for mortal remains creates a material representation of Black Hills regional history. Paranormal phenomena at Keystone Cemetery have been documented by paranormal investigators, historical researchers, and casual visitors over an extended temporal period, with reports describing ghostly apparitions, phantom sounds, and spectral figures appearing throughout the cemetery grounds. Visitors and investigators have reported observing translucent figures of humanoid form walking among grave markers, with manifestations appearing in period costume consistent with late nineteenth and early twentieth-century attire. Phantom laughter has been reported by multiple witnesses in various locations, with the emotional tone described variously as cheerful or menacing. Spectral figures have been observed walking along pathways and between grave markers, occasionally appearing to examine individual grave sites or interact with the physical landscape. Physical investigation of Keystone Cemetery has revealed electromagnetic anomalies concentrated in areas where spectral manifestations have been most frequently reported. Temperature measurements have documented localized cold spots in areas associated with reported apparition sightings. Photographic documentation of alleged apparitions has been captured using standard photography and specialized infrared or thermal imaging techniques. The consistency of reports regarding specific manifestations and their spatial locations has suggested a pattern of genuine paranormal phenomena concentrated in particular areas. The biographical connection between several reported entities and the Mount Rushmore project has suggested the possibility that trauma or hardship associated with that undertaking may have contributed to spiritual unrest. Keystone Cemetery continues to function as an active burial ground serving the Keystone community and surrounding region, with ongoing interments supplementing the historical significance of established graves. The cemetery has become recognized within regional paranormal investigation networks as a location of documented and significant haunted phenomena. Historical and genealogical organizations have directed increased attention toward documenting the cemetery's grave markers and burial records. The proximity to Mount Rushmore has made Keystone Cemetery a destination for regional tourists. The cemetery represents a material intersection of multiple historical narratives encompassing frontier settlement, industrial labor, and artistic ambition.