Special libraries and archival repositories come in every shape and size.  They can be divided into the following broad categories:

Research Libraries
These include large public libraries like the Library of Congress and the New York Public Library, special collections in colleges and universities, and historical societies and museums. 

Government Archives
There are government archives at the national, state, county, and municipal level.  Individual government agencies may also maintain archives of their own records.  These entities may have their own search engines and discovery tools that do not overlap with databases such as ArchiveGrid or WorldCat.

Community Archives
Often organized and run by volunteers.  Community archives have open access policies and welcome researchers to explore and use holdings with few restrictions.  Examples include the Interference Archive and the Lesbian Herstory Archives.

Local Museums, Historical Societies, Libraries, & Archives
Small-scale local repositories often have wonderfully rich collections and highly knowledgeable staff.  Look for repositories in the geographical vicinity of your subject to find sources in a range of formats. 

Institutional Archives
The records held by companies and organizations documenting their own operations and histories.  These may or may not be open to outside researchers.  Permission is usually required for access.

Private Collections
Personal papers held by individuals and families.  These may be processed or unprocessed materials and access may be strictly controlled.  Contact the administrators directly to inquire about using the collections.  Be sure you understand and can agree to any restrictions before undertaking research. 

1. Explore secondary sources and published primary sources. A thorough understanding of your subject will help enormously as you look through archival folders and boxes. Without knowing what to look for, you may miss important documents or waste time trying to decipher unrelated materials.

2. Read finding aids in their entirety. Every section of a finding aid, from the administrative information to the container list, will inform you of essential details. The biographical and historical notes will be particularly useful for putting the materials in context, and the scope and content note will let you know whether or not the collection contains material relevant for you. But the entire finding aid should be essential reading.

3. Closely review the repository's website.  In addition to the basics such as the hours of operation and street address, repository websites often contain a wealth of information that will help you make the most of your visit.  You may learn about reading room protocols, advance registration requirements, reproduction policies, and whether laptops and personal cameras are permitted, among other details.

4. Contact the staff by email or phone.  This step is essential. Always contact the library staff to let them know which collections you would like to use and when you plan to visit. The collections you need might be stored offsite and require advance notice for retrieval. In some repositories, appointments are required. Permission might be necessary before you can use certain materials. The reference staff at the library can also help you discover other materials that are related to your topic and provide answers to logistical questions that are not answered on the website.

"archives. The history of archives in New York City mirrors the broader development of archival management in the United States..."

Read the full article in the Encyclopedia of NYC (2nd ed) (login required).

Following are links to the websites of selected research libraries in and around New York City where you can find manuscripts, archives, and other primary sources.  Rules and regulations vary by institution, so always review the website and contact the staff before visiting. Look for "using the collections" or "visiting the library" pages for important details.

"Statues - New York Public Library - Lions" The NYPL Digital Collections.

To identify repositories that may hold material on your subject, consult: