Patent documents aren't just useful for the technical information they disclose. They can also be valuable documents for genealogical and/or family history researchers. Historical information on an inventor's location, associated people (such as co-inventors or attorneys), and even workplace (which may be listed as the assignee) can potentially be obtained from patent documents.
If the inventor's name is known, the fastest way to find their patent(s) is to use a database that allows searching by name. This can be done with many free search tools, though names prior to 1976 will have been machine-transcribed and may contain errors.
You will likely need to use advanced search (Google Patents) or structured search (Lens) in order to specify that you are searching for a name and where you expect that name to appear. Typically the best option (field) to search for this is assignee or inventor.
If the name you are searching for is very common, the name alone may yield too many results. In this case, you will need to narrow your results using one or more of the filters available in the search tool you chose. Jurisdiction and date range filters (if known) may be most immediately useful.
Note: Text, including inventor and other names, from pre-1976 patents has typically been obtained using computerized optical character recognition rather than human transcription. This means that searches sometimes will not retrieve any useful results even when the correct name is known and entered, because the software has in some way misread the text. In these cases, it's best to try to track down additional information about the patent (such as the issue date or patent number) and use that to search.
If you know the date the patent was issued or published, it is often fastest to go directly to the USPTO's search tools and search by issue date.
Format your search as follows, including all punctuation:
Exact date: YYYYMMDD.PD.
Year only: YYYY.PY.
The Patent Public Search help file includes information on how to search using a variety of date range tools.
Be aware that searching by publication date and using a date range can quickly get you too many patents to feasibly browse through. Older patents will often have very little bibliographic information available on the search page, so It's best to narrow your date range down as much as possible, preferably to a single day, before searching.
If the information you have is limited and is not getting you to the patent document, try looking in the Gazette of the United States Patent Office. These hefty volumes listed information about all the patents granted in a given time period, including inventor names, patent numbers, and issue dates—all key information for locating the document. Volumes of the Gazette are now viewable and searchable online via HathiTrust and can help supply the bibliographic information needed to get to the patent document.
The USPTO did not publish patent applications prior to 2001. Beginning with the American Inventors' Protection Act of 1999, U.S. patent applications began to be published. If the person you are researching may have filed a patent application in 2001 or later, you may be able to locate that document using the USPTO's Patent Public Search. Patent applications prior to that time were not published and are most likely not findable.
By default this database searches both applications and granted patents. In the databases pane, uncheck the boxes for USPAT and USOCR to search just applications.