Libraries provide various levels of data for various public and private consumption. For example, the Library of Congress is the largest library in the world with more than 147 million items on 838 miles of shelving. There are several different formats of databases which are made up of different mediums, such as magazines, reference books, and others. The value of such databases is directly proportional to the ability to access and search the information by various methods such as by author or keywords, etc.
Some library databases offer only a portion of a written text, while others show the full text. General Interest includes journals and magazines with a variety of topics. Some include very specific topics and disciplines and narrow the search enormously. And still others zero in on a specific subject, which may miss out on taking in all of the data needed. However, narrowing a search down can often help as a researcher to analyze a particular subject of interest.
There are many very good genealogy libraries. Some hold specific accounts and journals of individuals in a particular region or area of the U. S. I have listed the top ten largest genealogy libraries which should be at the top of a researcher's "Check it out" list. Whether you or your ancestors lived in the state in which the library is located, the researcher should find something of interest in these libraries. The libraries with such extensive collections include: Allen County Public Library in Fort Wayne, Indiana; Clayton Library in Houston, Texas; Family History Library in Salt Lake City, Utah; Library of Congress in Washington D.C.; Mid-Continent Public Library in Independence, Missouri; National Society Daughters of the American Revolution (DAR) in Washington D.C.; New England Historic Genealogical Society Research Library in Boston, Massachusetts; New York Public Library in New York City, New York; and Public Library of Cincinnati & Hamilton County in Ohio.
A good listing of genealogy Libraries can be found at: Directory of Genealogy Libraries In the U.S..
Many local public libraries, city and county, have their own collection of genealogical and local area history-related materials. Some are accessible by the Internet, and some you will still need to physically travel to and search their indexes for ancestral data.
Then there are the various state and county genealogical societies which carry on a tradition of collecting local family, city, and county histories. Many are repositories of unique collections given to them by area families and have specific surname information. Some have indexed the materials and sell such indexes in a book form, while others have their listings online.
I have discovered pertinent indexes, tables of contents, databases, and other forms of data in some of the most unlikely of areas. I have found the index of data concerning a particular county under the control and jurisdiction of a private individual in a far off county or another state. You never know who has data about your family line until you start making inquiries.
The last source of libraries is sometimes overlooked and that is the private or individual library. Some genealogists have collected data, articles, photos, and profiles for several decades and do not realize the importance of their own library to others. Don't be shy to ask relatives about who in the family is the family history historian in the bunch. Taking an interest in your own family history and staying in contact with the records-keeper of the family can yield a researcher much critical data. Often I have received packets of photos and data from elderly, distant cousins who feel relieved they have found a home for their cherished collection. Some cannot find anyone in their direct family who have any interest and threaten to throw it all away when they pass on.
And now, we come to your own library. I took some measures to convert the tiny cellar of the family garage into a fireproof archives room. I felt it only fitting that if people trust me with their collections, that I should keep them safe. Ultimately, I may have to donate the whole collection to a local historical society as I too have run out of family members interested in family history.
Organization is everything, and a researcher should spend time cataloging, indexing, and keeping photos and original documents in some kind of acid free protective covering, whether it be folders, notebooks, or plastic sleeves. You don't have to be a librarian to have a library, but remember, as private as your library is to you, a library is just not very useful if it cannot be shared.