The I-Card is a paper record that the City of New York adopted in 1902 to document the required building improvements of tenements and multiple dwelling buildings, and for regulating their use. It was a product of the Progressive Era, a period around the turn of the last century when building codes, sanitary conditions, and safety issues in tenement housing all came under greater scrutiny.
Thus, the city came up with a way to track the required alterations that certain buildings made over time—the “I” in “I-Card” refers to these improvements. Such regulations demanded that a tenement had proper and adequate fire-escapes and means of egress through the roof, as well as proper ventilation and lighting in interior areas.
Following the new legislation, the Tenement Housing Department had to locate and review all 83,000 tenements within the city. The department thus developed a standard means of inspection that could be learned quickly by their employees and filed so that these cards could be accessed readily for future inspections. These cards also contained drawings or diagrams to show the exterior and interior arrangement of each tenement house.
For buildings without a Certificate of Occupancy, which was not required until circa 1938, the I-Card can be accepted as the legal record of existing occupancy as of the last date indicated on the card. However, buildings with I-Cards may have or need more recent legal occupancy records if any lawful alteration or conversion work was performed in the building beyond that date. Not all houses built before 1938 have I-Cards—this is likely because they were misfiled, lost, or inadvertently destroyed—but if a building was never considered multiple-dwelling (i.e. housing three families or more) or inspected as such, then it would never have acquired an I-Card in the first place.