Duffy's Cut Mass Grave. Nearby is the mass grave of fifty-seven Irish immigrant workers who died in August, 1832, of cholera. They had recently arrived in the United States and were employed by a construction contractor, named Duffy, for the Philadelphia and Columbia Railroad. Prejudice against Irish Catholics contributed to the denial of care to the workers. Their illness and death typified the hazards faced by many 19th century immigrant industrial workers.