E. D. McAllister seems to have been Elmer D. McAllister, a machinist who lived at 101 South Main Street in Barre in 1908 and around the corner at 53 Ayers Street in 1910, according to the city directories. He does not seem to have been a professional photographer. I haven't done enough research to tell you how long he lived in Barre. We just acquired a collection of about 28 postcards, most of which have his stamp on the back.
Paul Carnahan, Librarian
Vermont Historical Society, Barre