To learn more about the history and evolution of city directories, see:
Each entry typically lists the person's name, occupation, and a business address, followed by a home address, which is preceded by an "h."
New York City Directory, 1857
Unlike later "business directories" which are arranged by type of trade or business, city directories are arranged alphabetically by the resident's surname. The name of a person's business may also be listed separately, e.g.:
Ambler Henry S. coal, 22 Elizabeth h Brooklyn
Ambler John C. notary, 29 Wall, h. 80 Clinton pl.
Ambler John G. dentist, h 31 Washington pl.
Ambler Sam M. pianos 358 Bowery h. 131 Eldridge
Ambler Wm strawgoods 24 Warren h. 51 W. 29th
AMBLER & COLLARD, coal, 22 Elizabeth
Since business names are also listed alphabetically, it may be difficult to associate your relative with the name of a non-eponymous business, or one where the family surname appears but not as the first word. In the example above, for instance, a researcher looking for the name of the business owned by Collard would not be able to find it unless he or she knew that the first name listed was Ambler.
Even if you are not lucky enough to find the specific name of your family business in a directory, you can use the business address to search in other sources (such as street directories or newspaper databases) that may lead you to the business name.
In most large American cities, city directories began to be published around the beginning of the 19th century. For smaller cities, directories may not have appeared until the late 19th or early 20th centuries. Coverage varies by publisher, but most include only heads of households and those owning or working in a local business. Most directory publishers gathered data through a door-to-door canvas, relying on the voluntary cooperation of residents. If the resident was not at home, an information slip was left, which the resident may or may not have chosen to complete and return to the publisher. African-Americans, when included, are generally identified by a racial designation (e.g., "col'd"), or may be listed in a separate "colored" section. Women who are running a business or selling goods or services are also listed (otherwise, women appear only if widowed).
More than just a listing of names and addresses, city directories usually also include some (or many) business advertisements, and may also have a separate business section or "commercial register" at the back, arranged by category rather than simply alphabetically. So make sure you explore beyond the alphabetical listings of names.
NYPL DIgital Collections Image ID 56790448
And don't stop with advertisements: city directories are wonderfully informative about many aspects of your ancestors' lives beyond mere business. They may include lists of clubs and organizations, government agencies, banks and insurance companies, churches, docks and wharves, ward maps, and many other details that will enrich your understanding of the community in which a historic business operated.
NEW YORK CITY DIRECTORIES
Regular publication of New York City directories dates back to 1786, when David Carroll Franks published the New-York Directory (available online through Columbia University Libraries’ Digital Collections). With a few gaps, city directories were published annually thereafter.
Free online sources for NYC directories:
Many early New York City directories are now freely available online through the following sources:
NYC directories available on-site at NYPL:
In addition to the directories freely available online through NYPL's digital portal, NYPL provides on-site access to directories through subscription databases, on microfilm, and in print (note that to preserve our print directories, they are only made available when not accessible online or on microfilm).
Subscription databases
Digital copies of early New York City directories can be accessed through several subscription databases that are available on-site at NYPL:
Microfilm
If you are looking for later directories, or can’t find the specific year you are looking for online, NYPL holds a nearly complete collection of New York City directories on microfilm.
NYPL DIgital Collections Image ID 1252841
Print copies
NYPL also holds print copies of many early NYC directories. To locate these in our online catalog, it is useful to know the main directory publishers, which include the following:
You can also try searching for New York City directories in our online catalog with the following subject headings:
DIRECTORIES FOR OTHER CITIES
Directories for cities and towns outside of New York City are also available, both online and at NYPL.
Free online sources:
Available at NYPL:
REVERSE DIRECTORIES
NYPL also holds a number of address or "reverse directories" on microfilm, which list both residents and businesses by address, rather than name. These are obviously very useful if you have the address of the business but do not know the name. They also provide information about surrounding businesses and residences, which helps to paint a fuller picture of the community in which your ancestor's business operated. NYPL's reverse directory holdings for New York City encompass the years 1929-1980 and 1986, with some gaps.