Patent Numbers Dating from 1836, patents have been numbered. Patent numbers are issued sequentially. The higher the patent number, the newer the patent. In the United States the patent system provides for the public disclosure of invention, while at the same time protecting the rights of the inventor. After this period of time the patent is in the public domain.
Patents provide current and historical information.
Use to identify some appropriate patent classification numbers for your search. Print Search Identifies Patent Citation and Abstract 1. Index of patents issued from the U.S. Patent and Trademark Office. 1951- Patent numbers are listed under each class and subclass on a year by year basis. So, you will need to search each year.