Under the New York State Social Service Law, the term Social Services District refers to the department of social services for each county, with the exception of New York City, where it refers to the New York City Department of Social Services.
Legal source
The social services districts are formalized in Social Services law ยง61, which states:
Social services districts. For the purpose of administration of public assistance and care the state shall be divided into county and city social services districts as follows:
1. The city of New York is hereby constituted a city social services district.
2. Each of the counties of the state not included in subdivision one of this section is hereby constituted a county social services district.
References
Social Services District (New York) Wikipedia(Text) CC BY-SA