Appointments of Postmasters through 1971 are on Ancestry.com
If you have a subscription to ancestry or know someone or a library that has a subscription go to the above link and then go to image 338 (beginning of Montgomery Co in 1900). Towns are arranged alphabetically and each is followed by the names and appointment date of postmasters for roughly 20 or 30 years. To find later dates just go to the next dated section for Montgomery Co and then find Harleysville again.
Dear Mr. Bucher,
Thank you for posting your request on History Hub!
We searched the National Archives catalog and located the Records of Appointments of Postmasters, 1832 - 9/30/1971 in the Records of the Post Office Department (Record Group 28) that should include the postmasters for Harleyville in Montgomery County, PA from 1900-1970. We also located the Records of Appointment of Postmasters and the Establishment of Post Offices, 7/1/1931 - 10/31/1971 in Record Group 28 that includes two digitized file units for Montgomery County, Pennsylvania. For access to the non-digitized records, please contact the National Archives at Washington, DC - Textual Reference (RDT1) 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 the RDT1. We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your research!