Faulstich was a pioneer student and collector of postal history. She campaigned extensively to have postal history recognized as a category at major exhibitions. She was a founder of the Postal History Society of the Americas (now the Postal History Society, Inc.). Faulstich helped the PHS through its early years as the first editor of its Postal History Journal, and as president from 1965 to 1967.
In her philatelic career, “Dee” edited Covers magazine, The Essay-Proof Journal and was associate editor of Western Stamp Collector. She wrote a stamp column in the Bergen (NJ) Evening Record and later in the Newark (NJ) News.
Faulstich built world-class collections of the postal history of the American Expeditionary Forces and the Canadian Expeditionary Forces in Siberia during World War I.