Depending on your area of research, there are many databases that the Library subscribes to that may be of interest. Some of these databases may be available to you in other venues either at a public library or through a university system, but to access the databases we subscribe to, you have to be on the campus of the Library of Congress. Many of them are archives of newspapers and their advertisements from around the country and can be helpful in finding information of a more local or regional nature.
The databases right below are good for those looking to study the modern industry but can also be good for doing historical research, depending on the time frame someone is interested in. The box below has databases are specifically for those doing historical research.
The subscription resources marked with a padlock are available to researchers on-site at the Library of Congress. If you are unable to visit the Library, you may be able to access these resources through your local public or academic library.