Dear Mr. Sevart,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located a series titled Records of Divisions, 1917 - 1920 in the Records of the American Expeditionary Forces (World War I) (Record Group 120) that includes records of the 120th Infantry Regiment, 30th Infantry Division in Box 111 (P 1241-30). Records of lower echelon units, such as companies, sometimes were incorporated into the files of the regiment. We also located a series titled Records of the 1st Through 338th and the 559th Infantry Regiment, 1/1/1916 - 12/31/1921 in the Records of U.S. Regular Army Mobile Units, 1821-1942 (Record Group 391) that includes records of the 120th Infantry Regiment. For access to both of these series, please contact the National Archives at College Park - Textual Reference (RDT2) via email at firstname.lastname@example.org.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT2. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your research!