Municipal Archives of the City of New York
The portal to the city’s myriad archives, including DORIS (see below).
New York City Department of Records and Information Services (DORIS)
The official database for New York City records, including census information, wedding and death notices, and other historical records.
New York City Landmarks Preservation Commission
The city’s agency for designating landmarks and historic districts.
New York State Archives
The New York State Archives publishes an excellent quarterly journal of work from the Archives.