Patient case files prior to 1899 were maintained in folio sized registers that usually contained two pages of summary information for each patient. Beginning in 1899, patient case records were maintained in individual folders. From 1900 through the early 1940s case files are fairly consistent in regards to their average size and types of documents they contain. However, the nature of files changed in the late 1940s as medical and psychiatric examination and evaluation techniques became more sophisticated and resulted in greater documentation. The files also experience another change in the 1970s and 1980s with even greater proliferation of medical and psychiatric documentation. In addition, there is more documentation concerning fiscal aspects of the patient's care.
From the description of Patient case files master negative microfilm, 1998-2001. (New York State Archives). WorldCat record id: 123527597
