Dear Mr. Kosinski,
Thank you for posting your request on History Hub!
Various offices within the Department of Defense have informed us that no agency of the Federal Government has ever compiled comprehensive lists of all individuals who served in the U.S. Armed Forces during World War II.
We suggest that you request a copy of their Official Military Personnel Files (OMPFs). OMPFs and individual medical reports for those who served in the U.S. Armed Forces and who were separated from the service prior to 1958 are in the custody of NARA's National Personnel Records Center in St. Louis. In many cases where Army and Army Air Corps personnel records were destroyed in the 1973 fire, proof of service can be provided from other records such as morning reports, payrolls, and military orders, and a certificate of military service will be issued. Navy and Marine Corps OMPFs were not affected by the fire. Please complete a GSA Standard Form 180 for each person whose records you are requesting and mail it to NARA's National Personnel Records Center, (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. For more information see Official Military Personnel Files (OMPF), Archival Records Requests.
However, please note that due to the coronavirus public health emergency, National Archives research rooms and museums are closed to the public until further notice and the National Personnel Records Center is servicing only urgent requests related to homeless veterans, medical emergencies, and funerals which may be faxed to 314-801-0764. We thank you for your patience and look forward to resuming normal operations when the public health emergency has ended.
World War II Army Enlistment Records are in the custody of the National Archives at College Park - Electronic Records (RDE) and are available via AAD (Access to Archival Databases) on the National Archives website at: https://aad.archives.gov/aad/. Click on "World War II" under the category section. A list of the databases relating to WWII will appear and select the first database to search the WWII Army Enlistment Records. Please note that this database only covers those that enlisted in the Army (to include the Army Air Corps) from approximately 1938 through 1946, and that due to gaps in the records, not all persons who joined the Army during this time period are included. The database does not include records of those that served in the Navy, Marines, or Coast Guard.
We hope this information is helpful. Best of luck with your family research!