Dear Mr. Wade,
Thank you for posting your question on History Hub.
For information on Mr. Lewis D. Harnett in Michigan and Ohio, you may wish to contact the state archives for each state for any personal papers or information on him during his time in each.
Vital Records (birth/death certificates, marriage licenses, etc.) are not considered federal records and are not kept by the National Archives. Please refer to local jurisdictions for these records. For more information see https://www.archives.gov/research/vital-records.
If you have not done so already, one of the best sources we have for genealogical research is census records. Information about census records can be found on our website at https://www.archives.gov/research/genealogy/census/about. Many of these records have been digitized and are available through our partners. For additional information about accessing these records, you can visit our website. You can also search for your grandfather and work your way back to his parents.
Other helpful links about doing genealogical research can be found below:
We hope this information is helpful in your research.
The National Archives and Records Administration