Dear Mr. Basoglu,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the series Enlistment Papers, 1798 - October 31, 1912 and Registers of Enlistments in the United States Army, 1798 - 1914 (M233) in the Records of the Adjutant General's Office, 1762 - 1917 (Record Group 94) that include military service files of the Regular Army. For access to the Enlistment Papers and M233, please contact the National Archives at Washington, DC - Textual Reference (RDT1) via email at firstname.lastname@example.org.
M233 has been digitized and is available on Fold3 as Army Register of Enlistments, 1798-1914; on Ancestry as U.S. Army, Register of Enlistments, 1798-1914; and on FamilySearch as United States Registers of Enlistments in the U.S. Army, 1798-1914.
Since the railroads were owned by private companies during this time period, NARA would only have custody of records of the US government that may have had an effect on railroad employees. We searched the National Archives Catalog and located 26 series in various record groups that pertain to railroad employees during the 1910s and 1920s. For access to these series, please contact the NARA reference unit listed in the various series descriptions.
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 RDT1 or other NARA reference unit(s) you contact. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your family research!