Dear Ms. Sutherland,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the series titled Draft Registration Cards, 1917-1918 in the Records of the Selective Service System (World War I) (Record Group 163) that are in the custody of the National Archives at Atlanta (RE-AT). As the draft cards asked for possible exemptions, it is possible your grandfather’s reason for an exemption is listed directly on the card. For access to and/or copies of these records, please contact RE-AT via email at firstname.lastname@example.org.
It is also possible that his reason for an exemption could have been recorded in the Docket of the Draft Board where he registered. We searched the Catalog and located multiple series of Local Board Dockets in Record Group 163 that include various Local Draft Board locations. For access to and/or copies of a particular docket, please contact the appropriate NARA location:
National Archives at New York (RE-NY) - Email: email@example.com
National Archives at Philadelphia (RE-PA) -Email: firstname.lastname@example.org
National Archives at Atlanta (RE-AT) - Email: email@example.com
National Archives at Kansas City (RM-KC) - Email: firstname.lastname@example.org
National Archives at Denver (RM-DV) - Email: email@example.com
National Archives at Riverside (RW-RS) - Email: firstname.lastname@example.org
National Archives at San Francisco (RW-SB) - Email: email@example.com
National Archives at College Park - Textual Reference (RDT2) - Email: Archives2reference@nara.gov
National Archives at St. Louis (RL-SL) - Email: firstname.lastname@example.org
We hope this is helpful. Best of luck with your family research!