This database covers institutional and commercial libraries that existed in what is now the continental United States from the time of first settlement through 1875. It records nearly 10,000 libraries.

The end-date of 1876 is important because in that year the United State Bureau of Education published its first comprehensive, national listing of libraries, entitled Public libraries in the United States of America; their history, condition, and management. Special report, Department of the Interior, Bureau of Education. Part I (Washington, DC: Government Printing Office, 1876). This massive work — 1187 pages — of facts and statistics began a continuous series of publications stretching down to the present. The present database extends this series of facts and statistics back to the first colonial libraries.

Most of the libraries before 1876 were very small, a few hundred books at the most; and most had a very short active life. Most libraries were membership organizations, which served the members who provided financing. Even small communities often had more than one library, each of which served residents of a particular geographical area; and in cities there also were often several libraries, each of which served different segments of the population.

The small size of the libraries and their short lifespan means that little information is available about most of them. Indeed, the record of the existence of many stems from an almost passing mention or a brief listing. Many more surely existed, but that likelihood by no means takes away from the utility of this database. In almost all cases the patterns that it reveals will continue to stand.