I paid a visit to the ETT's posted at Derrick Brashear's site,
http://www.dementia.org/twiki/bin/view/PRR/PRRDocuments
and found a 1935 Maryland Division; shows 4 daily stops at Iron Hill (all for locals, of course) and about 8 more flag stops. Some of the schedules were MU-operated.
The local interlocking tower in those days was listed as BIG ELK, and was shown as 2.2 miles west (south) of Iron Hill station and 0.9 miles east (north) of Elkton. Pesumably it was remote-controlled as PRR, with help from USS/Westinghouse, began consolidating interlocking plants, starting in the late 1930's.