Genealogical research is different from other historical studies inasmuch as researchers are often looking for specific details on individuals. Genealogical research is also usually directed at producing a kind of historical output that is distinctive from more general historical scholarship. Genealogists frequently aim to construct family trees with specific details on individuals like dates of birth, information on immigration, marriages, etc. whereas professional historical scholarship usually produces historically narratives written as articles or books. There is thus a difference between searching out specific details, and telling a story with a big picture. As a result, the method of finding materials for genealogy and for broader historical research can be different.
The archives listed in this guide may have relevant genealogical materials, but they also might not. The best way to go about genealogical research also is often through state repositories which maintain census databases, vital records like birth and death certificates, and so on. Also, sometimes archives are not the best source for genealogical materials. One can look at cemeteries, family Bibles, and other material objects that have genealogical information.
Many archives do work to assist genealogists, and even have genealogical departments. But the files are not organized into a searchable database on the basis of someone’s name or location. If you are looking for someone specific and you know they were involved in a community, an organization, or had a professional or personal relationship with an individual whose records are held by an archive, you can often look through those collections to find materials relating to that individual. Oftentimes collections have a correspondence section which is organized alphabetically by correspondent so you might find letters from the person you are interested in that can tell you about their life, and sometimes personal details relating to family members or life events.
Genealogical societies have put together useful research guides, including:
Jewish Genealogy Research in RussiaJewishGen databases